I think, I could be wrong, that if you look into this is terms of timing, you will find that Federal help for NY was either very late in coming or was attenuated in certain ways that were illogical. Eventually help would arrive, when any further delays would have been a little too obvious. You'd probably find the same pattern regarding federal help for California. Florida would be a good State to compare to. I don't have any data backing my hunch, just the pattern of Trump's vindictive behavior. If we looked closely enough there is a high probability we would find the same behavior even in Trump the child. Vindictiveness is a component of his sociopathic narcissism.
As an example, before Trump was elected, Obama cracked a few jokes at Trump's expense. Trump has ever since gone out of his way to undo everything that Obama did in whatever way he could and not miss any opportunity to compare himself favorably to Obama. This will continue until Trump's last breath. Neither New York's nor California's governor has been complimentary of Trump in the past, and they can expect little help from Trump, unless Trump politically has no other option, until they recant and sing Trump's praises...under the current dire circumstances they may be forced to do just that.