Hell, we have floods today all over the world. Extrapolating a world-wide flood from this fact is as untenable as extrapolating a world-wide flood from mythic legends.
Not certain what the argument is here, but, mine is that there were far more substantial and numerous floods in 10,200BC than is the case now by a very long shot. The Alberta flood alone must have seemed like a world-wide catastrophe to many Northwest Indians. And that's just one ice dam event out of what must have been thousands.