The isostatic rebound occurs where the glaciers held the ground down. It is very pronounced in the u.s. particularly in the great lakes region. But much of the country was not covered in glaciers in the last ice age. So what is it rebounding from? It isn't. And that is where the ocean gets deeper from melting ice. Rebound in the immediate vicinity of a great weight being removed is not a new thing. But that is not what most shorelines are dealing with.
He mentions the southern hemisphere at one point. and that it is where the most pronounced average depth increase will be. Because the water just changes form, and the weight is then distributed over the whole of the oceans. I think the tweak of adjusting the rebound in the glacial zones as a main force is a good headline, but makes it appear that ocean rise is not real or something.
Rock adjusting upward makes a difference in a localized way, but not globally. Perhaps tektonically on a geologic timescale. Finding a place where the ocean has not risen and featuring that as a generalization is disingenuous, methinks. Doesn't give solace to Bangladesh now, does it? Or florida.