I mean, it's a fair point. My stance on the Alien Butt Stuff? Fetishes. Alien butt fetishes. We have bigger butts than they do, and they want to have fun on their spare time.
Or, we could construct an alternate theory based on the Alien movie and facehuggers. Butthuggers?
"Oh, we finished the medical research ages ago, at this point it's all just about - I mean have you seen their asses?" Yeah, no, that checks out! I can only assume the aliens have failed to notice the existence of the Internet. Either that, or they have noticed and now they're staying even more lowkey because it's that or end up buried under a literal mountain of thirsty bottoms. Talk about an Area 51 raid...
(Don't get me started on the Alien aliens. I mean, their reproductive cycle obviously takes strong inspiration from that of spider wasps, but parasitoidism only works reliably when the supply of hosts is unconstrained. Given the creatures' evident intelligence and their capacity for rapid and apparently directed adaptation via horizontal gene transfer from their hosts, and given also the extensive variety of things that humans get horny about, you'd really expect to see a modus vivendi develop pretty quick, you know?)
I dunno, man. The Anti-Butt Brigade must not be the most consistent bunch.
Re: a modus viviendi, though - I'd rather not see Earth become a sex tourism location for the local star systems. After a few generations of selective breeding, we'd all look like Kim Kardashian.
Eh. I see no reason to imagine that extraterrestrials so similar to humans that they'd find any of us sexy, would also be so different from humans that their tastes in such matters never varied. Or, at the very least, that they wouldn't be interested in the range, the sheer butt-buffet our species has to offer, rather than uniformly focused on some Platonic ideal of the dumptruck.
That's what I'd hope, at least. But you're still right that there's a real risk here. Maybe that explains the weirdly targeted flagkill - not that I don't probably know one or two people who'd be here for that in theory, but from where I sit, it is a frightful prospect.
Or, we could construct an alternate theory based on the Alien movie and facehuggers. Butthuggers?