mojjjBeing underwater has (as far as I know) the following effects, and
only the following effects:
1. Non water-capable weapons are disabled
2. Non amphib units cannot move
3. Units cannot cloak.
Energy generation is not on that list, and indeed, an underwater singu continues to work and generate energy
Antinuke, on the other hand, is a bit different. Since the interceptor that antinuke fires is an weapon, and that weapon is not water capable, it gets disabled
Most other buildings follow these rules, with bertha, cereb, trinity, zenith, ddm, lucifer, and raveparty all being unable to fire their weapons.
Starlight, however, is an exception. Since the starlight laser is actually water-capable, an underwater starlight will work perfectly fine, despite starlight not being able to be built underwater