I haven't double checked this, but I strongly suspect they're bandwidth limited by the total amount of uplink/downlink they have, not the inter-satellite bandwidth.

Inter satellite links are basically fiber, just without the fiber (instead they just point the laser in the right direction and rely on the fact that space is empty). Up and down has to use valuable radio spectrum, handle interference and atmospheric effects, etc.

Those same satellites will cover land as well, right? I would guess that they are hugely over provisioned for their maritime usecases in support of their main mission.

You wind up with the same satellite average satellite density across the middle latitudes anyways because the orbits are very low for satellites. Any particular satellite will eventually service every cell (except for those above the inclination of the main constellation iirc those will eventually (tm) be covered by separate satellites in more polar orbits) between 53N and 53S, which is the orbital inclination of the majority of the constellation. Because of this you don't really have any distinction in function between land and sea servicing satellites because any given satellite will be both.