I've always found this a weird comparison. There is no more important use of water than providing food. I love tech and earn my living from it, but the importance of food cannot be overstated.
I think the criticism here is that they're pumping that water in from the Colorado river based on a pricing schema that makes it artificially cheap t grow water intensive crops in a very arid region. If the pricing were modernized and rationalized those pistachios would be grown somewhere that has more rain fall. Moreover a lot of that water is transported with the pistachios out of the watershed so it creates 2nd order problems.
You could also argue that Amazon data centers are crucial commercial infrastructure that used for a lot of logistics necessary to move food around.
Its not a bad comparison because pistachios are a cash crop, not a staple crop. That is to say, pistachios aren't grown to keep people fed, they are grown for economic profit
You find growing an incredibly water heavy crop in a place that doesn’t have the water supply to do so a weird comparison? And it’s not even a food that’s needed, so you can’t stand on that either.
Saying "if it's edible then it doesn't matter how much water it uses, it's justified" isn't a good position to take.