Putting things into perspective is not minimising the problem. We literally have to do this to prioritise where our efforts can be useful.

Your argument makes sense if ai datacenters were using something close to like alfafa farming but the difference between them is soo massive it does not make sense.

Reducing pollution is a much better problem to fight for

I am guessing (not asserting) that there is a sort of cap on water used for agriculture. It's possible we've already reached it. (?)

So, on the matter of scale: there likely isn't a cap on water use of these datacenters. Both the heat emission and usage levels for these systems will likely go up unless there is a fundamental technical breakthrough.

On the matter of utility: As a sibling of GP mentioned, the utility of food is clear.

On the matter of polution: I am not remotely read on waste water and contamination due to industrial agriculture. Is this also something where the judgmental scale is tipped in favor of food production vs cooling systems?