All you need to do to show this is a simple steady-state calculation: if the population size is going to stable, each man of reproductive age must impregnate on average 2/(1-m) women, where m is the child mortality rate (pre-reproductive-adulthood). The only way this is 100 is if m is 0.98, which is ludicrously high (and also impossible given female reproductive biology unless you counted an extraordinarily high rate of early miscarriages and even then it's a stretch). I don't understand why all the other calculations with highly dubious assumptions are worth making if one just wants to know what is "likely".

If you want to know the entropy of differential male reproductive success (roughly, "does it matter?"), and whether it could drive pro-promiscuity alleles to fixation, that's a totally different question and isn't addressed by any of these calculations. (The "not more than about 12-16" thing is relevant.)

Also, what's with the fixation on paleolithic humans? There are super-Y lineages from neolithic times, which are plausibly in part due to promiscuity (but also cultural maintenance of power), and which could have evolutionary implications: https://www.discovermagazine.com/the-sciences/1-in-200-men-direct-descendants-of-genghis-khan.