I feel like I should start a running archive of every comic strip that's like this, complete with overanalysis of what's going on.
* Stilted, sterile sounding analysis of an issue? Check.
* Extremely vague description of what's disapproved of? Check.
* Misunderstood Bible quote? Double check, since that's apparently the punchline. (Bonus round: "Thou shalt not judge", being used to judge others? Check.)
But the weirdest part is "those who use religion to mask and make right their intolerances"? Aside from the giveaway ("Let's see, how do I talk about gay issues, yet NOT talk about gay issues? Wait, I know, this is subtle..!"), the idea is just odd. Apparently the charge is that no one actually thinks anal fisting is immoral or something to be frowned upon from a religious point of view. Nope, that's just the cover story people are using. They dislike it for reasons that have nothing to do with religion!
I'd question the guy's sincerity, but at this point I think it's truly the case that many people have trouble fathoming how any sexual activity, short of rape and the like, can be immoral or wrong or a sin. The idea of sex having any sacredness to it, or end beyond pleasure first and foremost, is not rejected - it does not register at all.
I'm actually waiting for the day a woman accuses a man of anally raping her, and for people to get really worked up because she made it sound as if the anal part of the rape was particularly vile, as if she was judging that some sex acts are less pure than others. Eventually, even rape will have the alternate definition of 'being made love to against one's will'.