Whatever you recoat with, will adhere to what's on top, and its ultimate bond to the shell will only be as good as the bond of what's under it.

But . . . heavy coats of epoxy (Zeron) do 'hold stuff in place'. I've seen epoxy hold nearly loose plaster down for years. But, if it moves, gives, or wiggles under load, it's got to come out.

Ben