Change of sea level in relation to sea ground

[Studiot]

That doesn't make sense.

I think that's a trifle harsh.
I didn't even say I agreed with the proposal, I was just trying to clarify it so we are all talking about the same thing.

In particular, unless the local surface of the sea (regardless of how it got there) is coincident with the mean level (yes I know it's the same as the geoid for practical purposes) it will experience a different gravitational acceleration ie stronger or weaker gravity, increasing from A in the direction of B in my diagram.
So if B is below mean sea level as shown then it will experience stronger gravity, simply because it is closer to the centre of the earth. It cannot be any other way.

This has nothing to do with tides or isostacy.

Similarly the sea bed below B is where it is.

My interpretation of the original proposal is that the stronger gravity at B is attributed to the extra height of mass I have noted as L in my diagram.

Again I do not say I agree with this explanation, but I think that was the original point for discussion.