> This is a illogical position to hold, because clearly nobody applies that same logic about everything else the federal government spends money on.
That doesn't make it illogical, to make it illogical you'd have to do something like identify a fallacy. The same logic does apply to most of the things the US Federal government spends money on; the US baby boomers built a really stupid system that has destroyed a lot of potential for prosperity. In the US, anyway, China has been having a great time.
> If Texans want ...
I don't know where you're going with that paragraph, so I suppose I'll just agree with it. Doesn't sound entirely reasonable to me (US States aren't supposed to maintain things that look like armies and the idea might fall foul of that; but it also might not).
> ... It's a zero sum game: as a Californian, your tax dollars (whether state or federal) are now going to more objectively horrible things ...
The ideal would be Trump cuts spending, cuts taxes and then the Californians take their taxes and spend it on science funding.
I doubt that is going to happen, but the problem here is the taxes and the stuff Congress is going to be funding instead. Complain about that. If it was just a case of cut spending-cut-taxes then there is nothing stopping US citizens funding science to the same tune with the same money in a way that is more responsive to the details of what is going on. It was always a bad idea to route it through the Federal government, they don't have the bandwidth to debate this sort of issue when the world is looking like it might descend into a large multi-front conflict that could end up worse than WWII and there are riots and military deployments inside the US. It isn't important enough to deserve Congressional attention.