Giving in to people who are truly unreasonably offended (by proxy, for social validation, and so on) rewards and incentivizes the behavior, and in fact I believe you have an ethical obligation not to allow people to do this. Promoting antisocial behavior is antisocial.
To be fair, gundmc's original comment was rather prosocial as these things go:
>I find this use of "Catholic" pretty offensive and distasteful.
They didn't claim their preferences were universal. Nor did they attempt any personal attack on the person they were responding to. They simply described their emotional reaction and left it at that.
If everyone's initial default was the "gundmc approach" when they were offended, the internet would be a much nicer place :-)
So yeah, as far as I'm concerned, everyone in this comment chain is simply lovely :-)
It's worth having some grace about it though.