What did Luther mean by, "They are teaching me to be rude"?

I came across this one on the Christian Forums Lutheran board:

Toward the end of Luther's life, his poor physical health was said to have made him short-tempered and even harsher in his writings and comments. His wife Katharina was overheard saying, "Dear husband, you are too rude," to which he is said to have responded, "They are teaching me to be rude." What did Luther mean by this?

I am particularly interested in who Luther thought the "they" was... Did Luther believe he was under some sort of spiritual attack? Possibly somewhat like Paul's "thorn in the flesh"? However, according to Paul this was done to keep himself from being proud, not to make him rude.

This quote is probably getting some attention because of Wikipedia:

His poor physical health made him short-tempered and even harsher in his writings and comments. His wife Katharina was overheard saying, "Dear husband, you are too rude," and he responded, "They are teaching me to be rude."

Wikipedia actually documents the quote: Spitz, Lewis W. The Renaissance and Reformation Movements, (St. Louis: Concordia Publishing House, 1987), p. 354.  There Spitz states of Luther's final days, "Sick and constantly apprehensive about the danger of war, he became short-tempered and even harsh, though in behalf of the cause and not from personal peevishness. In response to Kathie's chiding, 'Dear husband, you are too rude,' he retorted, 'They teach me to be rude!'" Spitz provides no documentation.

Owen Chadwick points out the statement is from Luther's Table Talk:

The characteristic memory of Luther is of a man presiding at his own table, with is his colleagues and friends around, arguing with him, or listening to his divinity, his politics and his humor, One of the friends shamefacedly took out a notebook and began to jot down Luther's remarks. The habit spread, and twelve different reporters made collections. Luther sometimes mocked but neither resented nor forbade these deferential scribes. Twenty years after his death, one of them, Aurifaber, published a collection from a variety of collections. Thenceforth Luther's Table Talk became a classic of the Reformation. Rude and outspoken he might often be; 'Dear husband', said Catherine, 'you are too rude'. 'They teach me to be rude,' replied Luther. He was so outspoken that his enemies leaped to make capital out of the Table Talk. It is unreliable as a source for details of history, particularly when the events occurred many years before the date of the reported conversation; and Aurifaber's text was not untouched by improvement or interpolation. But it is a unique and authentic picture of a man and a divine; he who would understand Luther's person and mind cannot neglect it. It is impossible to apply any epithet to him less than the old classical epithet magnanimous, in its original sense of great-hearted. (Owen Chadwick, The Reformation (London: Penguin Books, 1964), 74-75

The quote turns out to be a Table Talk utterance recorded by Jerome Besold (see LW 54:467). While I'm not aware of any official English translation of the entire comment, Preserved Smith (a man fluent in Luther's Tabletalk) sets down the following context in regard to Luther's dealings with the Sacramentarians. It appears Luther had particular people in mind with a particular theology when he made the comment:

One of the lesser religious leaders of the time, usually classed as an Anabaptist, though he aspired to found a new sect of his own, the "Middle Way," was a certain Silesian gentleman named Casper von Schwenkfeld. He had been known to Luther for a great many years and detested for his heresy concerning the nature of Christ. Submitting his opinions to the theologians who met in the Congress of Schmalkalden early in 1540, Schwenkfeld was warned of his errors by them, whereupon he had the poor judgment to appeal from them to Luther. The opinion of the latter, together with his terribly rude answer, are recorded by Besold, November 8, 1543:

Schwenkfeld sent the doctor his book on the humanity of Christ, entitled Dominion. Luther said : " He is a poor man, without genius or talents, smitten like all the ranters. He knows not of what he babbles, but his meaning and sense is : l Creatures are not to be adored, as it is written : " Thou shalt worship the Lord thy God and him only shalt thou serve." ' Then he argues : * Christ is created, therefore we should not pray to the man Christ.' He makes two Christs. He says the created Christ, after his resurrection and glorification, was transformed into a deity and is therefore to be adored, and he foully cheats the people with the lordly name of Christ, saying all the while that it is for Christ's glory ! Children go to the heart of the doctrine with : 'I believe in Jesus Christ our Lord, conceived of the Holy Ghost, etc.,' but this fool will make two Christs, one who hung on the cross and the other who ascended into heaven, and says I must not pray to the Christ who hung on the cross and walked on earth. But he let himself be adored when one fell down before him, and he says : ' Whoso believeth in me, believeth in him who sent me.' This maniac has stolen some words out of my book." . . .

Katie said : "Dear husband, you are too rude." Luther answered: " They teach me to be rude." ... To the messenger he answered: " My dear messenger ! Tell your master Schwenkt'eld that I have received his letter and pamphlet. And would to God he would stop! Formerly he kindled a fire in Silesia which is not yet quenched and which will burn him eternally. And he adds to that the heresy of Eutychianism on the creation of Christ, and makes the Church err, as God has not commanded him to do. The senseless fool, possessed of the devil, understands nothing and knows not whereof he babbles. But if he will not cease writing, at least let him leave me in peace, untroubled by the books of which the devil has purged him, and let him take this as my last judgment and answer : The Lord rebuke thee, Satan, and may the spirit which called you, and the race you run, and all your fellow sacramentarians and Eutychians, go with you and/your blasphemies to perdition." . . .

Source: Preserved Smith, The Life and Letters of Martin Luther, pp. 406-407. Unfortunately, Smith provides no documentation either.