Melt water pulse 1a was likely caused by a meteor strike to the massive North American ice sheet resulting in something like a 100’ foot rise in global sea levels.

The global flooding resulting from such a cataclysmic event likely would’ve created tsunami style floods much larger in places than the amplitude of the total sea level rise after the chaos.

Randall Carlson has a great presentation on JRE (#606) where he touches on a lot of the evidence around this cataclysm. It’s so interesting.

There are theories pointing to mega floods occurring cyclicly every 12,000 years because of a pole shift.

While I would not reject the idea flat out, it seems a bit unlikely that a (global) flood managed to reach such height and submerge the pyramid for long enough to impact the rocks with sea erosion.

I'm not a geologist but I would assume it would take decades or centuries to cause rock erosion. And then the flood would just vanish somewhere I guess.

It doesn't really seem like a theory that I feel compelled to consider. I haven't looked at the video so perhaps I have missed some point or misunderstood the thesis.