These cities declared 'sanctuary' status because they never expected illegals to get that far North.
They did it as a general anti-America woke statement thinking it was a meaningless gesture.
For some inexplicable reason, they really truly expected all the illegals to stay in Texas which they were happy to sabotage.
It is like someone living in downtown NYC claiming to be an animal lover absolutist. That is all fine an good until the elephants, lions, and gorillas, actually show up. How are we going to feed all these? How can we take care of them?
Showboating made them feel good, superior, and 'enlightened', until it comes time to pay the bill. Now they are all crying like babies about a problem they created, and specifically endorsed and supported.