If the US ended up damaging power plans and desalination plants, that would mark a clear inflection point in the number of "friends" the US has militarily, economically, and politically. Sure, Israel would still be a big fan, and maybe Saudi Arabia, but otherwise the US would become a pariah.

It would be damaging to Iran and potentially hundreds of thousands or millions would die.

That's a lot of blood debts.

There is no way the US would walk away from that situation into a better outcome.