Where is the line?

The above cartoon was published in the October 16 issue of the Arizona Daily Wildcat, the University of Arizona's newspaper. Two days later the newspaper issued an apology, said it fired cartoonist D.C. Parsons, and said the staff is reviewing its editorial policies. And, of course, the newspaper editor was quick to do the whole "his [Parsons'] views do not represent the views of the Wildcat staff, nor does the Wildcat represent the views of the university" disclaimer.

Parsons also apologized, explaining that the cartoon "was not intended to offend." (Not sure how, but...) He said:

"It was based on an experience from my childhood. My father is a devout conservative from a previous generation, and I believe he was simply distraught from the fact that I had learned (from The Simpsons) what homosexuality was at such a young age.

"I have always used humor as a coping mechanism, much like society does when addressing social taboos. I do not condone these things; I simply don’t ignore them. I do sincerely apologize and sympathize with anyone who may be offended by my comics...but keep in mind it is only a joke, and what’s worse than a joke is a society that selectively ignores its problems."

I find this cartoon troubling, and wonder what the editors were thinking allowing it to run. But I wonder, is this a freedom of speech issue? Is there merit to allowing these views to be shared, if for no other reason than to provoke dialogue and, hopefully, to emphasize just how off-base and dangerous this type of speech is?

Is this offensive humor worthy of a cartoonist losing their job, or simply a case of a joke that fell flat? Where is the line where humor and comics are concerned?