The water argument rings a bit hollow for me not due to whataboutism but more that there's an assumption that I know what "using" water means, which I am not sure I do. I suspect many people have even less of an idea than I do so we're all kind of guessing and therefore going to guess in ways favorable to our initial position whatever that is.
Perhaps this is the point, maybe the political math is that more people than not will assume that using water means it's not available for others, or somehow destroyed, or polluted, or whatever. AFAIK they use it for cooling so it's basically thermal pollution which TBH doesn't trigger me the same way that chemical pollution would. I don't want 80c water sterilizing my local ecosystem, but I would guess that warmer, untreated water could still be used for farming and irrigation. Maybe I'm wrong, so if the water angle is a bigger deal than it seems then some education is in order.