One rationalization might be that the deterrent effect is so great, that the process of confiscating liquid containers makes SURE that no dangerous liquids are brought to the portal.

A TSA that cared about passengers would run a randomization process, so somebody who had to give up their water bottle could get a DIFFERENT one handed to them at the end of the screening process. Hard for the bad guys to game THAT system. Turn in a bottle, get a chit for a replacement from yesterday's bin.

What may have happened is that the TSA *wanted* bomb disposal presence at every portal to add to the theater effect, and they said: "You're kidding, right?"

Or else they thought one level deeper (I know, a rare event) and concluded that bomb disposal suits could *scare* the sheep in the queue and trigger them to ask the hard questions about the water carnival that everybody should be thinking.