Well, of course I am.
I'm likely one of the only people reading this thread thinking about how that girl is effectively being used to boost a stupid sexist conversation that will likely continue to hound her in her teenage and adult years as she grows to have the "boobs" and "ass" that the many, many guys on GAF and elsewhere are pining for. Because this thread, and most of GAF, is largely men who've never experienced this shit.
Look, the answer to this conversation is not "why not both?". The answer is to stop the fucking conversation and accept that everyone can and should have their own tastes that no one needs to question in the first place.
As I said in the last thread about this subject... It really depends on the audience. Because there are a number of women who are fine with the discussion. It doesn't affect bodily autonomy, not is it inherently sexist.
That said, there are also a number of women who would be uncomfortable with it. It's really better saved for closer friends/tight communities etc. Which is why I said the thread was iffy in my response to you.
I noticed you admitted your initial reaction was an overreaction, so I won't harp on that.
Finally, as for the actual subject of this thread... It looks like most people are saying it's juvenile, but not necessarily sexist. So I can already see why the discussion ends up this way - "it's juvenile" vs "who cares if it's juvenile"?
Realistically, the only route (which has already been presented) is showing this guy is a jackass in all aspects of life.