My answer is as follows:
“...neither shall all flesh be cut off any more by the waters of a flood..”
Perhaps the answer to your inquiry lies in noting that some casualties from a tsunami is hardly “all flesh” as described in the Biblical account of the flood.
He doesn’t mention a tsunami in his post, he says the waters of the earth are about to rise, suggesting it will be global in scope.
If a tsunami fits his description, then why not the tides? They rise and fall every day, and are much more global. His prediction or “prophecy”, by my reading, implies something more than either of those things, such as a global rise in sea levels like the global warming alarmists predict.
The only “flood” that I know of prophesied for the end days is this one (and it doesn’t sound like what he is talking about):
“15 And the serpent cast out of his mouth water as a flood after the woman, that he might cause her to be carried away of the flood.16 But the earth helped the woman by opening its mouth and swallowing the river that the dragon had spewed from its mouth.”