Your point about the differences in sexual appetites of Neanderthal vs Hss makes sense.
We also don't know, I am surmising, whether Neanderthal women were having a menstrual cycle in the manner of modern women.
This would make a large difference in the potential attractiveness, as well as viability of cross-breeding attempts.
Exactly! We have no idea whether Neanderthal and Cro-Magnon mating periods or fertility patterns matched up. A chimpanzee female for instance will generally not mate again for several years after giving birth. Was a Neanderthal more like that, or more like us - in terms of mating? We don't know.
Now of course in the grand evolutionary tree the Neanderthal was considerably closer to us, to say the least, than to a chimpanzee, but the point is that any number of additional factors could make a critical difference, such as menstrual cycles. So, in my view, the burden of proof in light of all the evidence is on those who would argue Neanderthal/Cro-Magnon admixture, and "because they were there" just doesn't cut it for me.
Another question: Did Neanderthal males have a 'pheromone trigger' as so many mammals do? A pheromone trigger that a human female would never trigger. Who knows? We don't. We never will. And the beat goes on!
So, all this talk about men having sex with chickens and goats and dolphins and whatever misses the point entirely IMHO. In fact, this is one of those very rare times when I would say an argument seems revealing of androcentric thinking.
And the reason why I'm excluding Cro-Magnon male/Neanderthal female pairings as any kind of general rule is because we don't find mixed communities in the archeaological record, and in order for those admixtures to remain in the ultimate human gene pool, you have to have the Neanderthal women stay in the Cro-Magnon community.
And who the heck knows if that's even conceivable. Could they be domesticated? No one has the slightest clue. The assumption itself is yet another example of 'humanizing' Neanderthals in my view. For all we know, a Neanderthal female would never do anything but bite, kick, and claw until you killed her or let her go.
One way to guess: were the Neanders as fascinated with the moon (and its cycles) as Hss? Were there lots of marks-of-groups-of-28 on bone chips and cave walls in Neander settlements?
No? That may be the dog that failed to bark, metaphorically speaking.