From the text:
If the function of comedy is to correct men's vices, I do not see why any should be exempt. Such a condition in our society would be much more dangerous than the thing itself; and we have seen that the theater is admirably suited to provide correction. The most forceful lines of a serious moral statement are usually less powerful than those of satire; and nothing will reform most men better than the depiction of their faults. It is a vigorous blow to vices to expose them to laughter. Criticism is taken lightly, but men will not tolerate satire. They are quite willing to be mean, but they never like to be ridiculed.
Comedy serves to expose men's vices.... to the men/women themselves. Some people attacked the play because they didn't like the way they believed they were being portrayed..... and the didn't like being made fun of. As far as being justified in their attacks, their anger wouldn't be considered odd. People need to learn to laugh at themselves.... or possibly change.