I really don't have a big problem with the climate change possibilities of YD or even the possibilities of a aerial meteor explosion during those times.
Like you, I do have a big problem with the events extinguishing Mega Funa and mankind of the time.
If it did, Goshen, Cougar, Folsom and Dalton cultures would never have existed. Smaller animals like caribou, moose ,elk and giant bison would have went away also.
Agate Basin, Eden and the Archaic explosion of numbers and diversity of artifacts would never of happened.
Little mammoths on Wrangle Island and Santa Catalina would not have been there 3,500 years ago waiting for boater to eat them.
I am glad science errrr well, some folks in science have put Humpty back together again.
Zuma