First, the name of the guy Bethesda hired who has an IQ of 60 who decided that Argonians should not be able to attack underwater. I want to avoid anything he's associated with in the future.

Second the name of the guy who hired the guy with an IQ of 60 and let him make decisions.

Third, is there a mod, and where would I find it, which makes Argonians the natural underwater predators they should be?

In all my years of playing, I'd never played an Argonian until recently. Now here I am a little while ago playing an Argonian DID character, when suddenly I am attacked by slaughterfish, and... I'm completely helpless. I can't fight, bite, or spellcast, and what the heck kind of aquatic humanoid would be that helpless underwater? Imagine a croc that couldn't bite, eh?

No race can attack underwater. It's a simple mechanics thing the devs decided not to bother with for this game. Hopefully they will allow unarmed attacks underwater in the next game, but if weapon attacks are allowed they should drastically decrease the damage they would cause.

Strange, there doesn't seem to be mods that allow underwater combat.