I think the main hole in their theory is that there is irrefutable proof that the Clovis First Theory is dead.
Unless they can come up with something better than a Clovis point as an indication of a new factor around 11,000 years ago, this theory holds no water - not even ice.
Why did man live here for over 30,000 years without eating into extinction all the ice age megafauna, and then all of a sudden, 11,000 years ago wipe them out??
Some cultural change?? New "invaders"?
Maybe 11,000 years ago they invented the chilli cook-off?