I had recalled that FEMA's charter also included "man caused disasters"
even though they are widely look at as being responsive to natural ones.
They did send plenty of money to NY to clean up after 9/11 and the world trade center "man caused disaster". That one wasn't very "widespread" either. It was pretty much all in a concentrated area.
With AGW there are perhaps less natural ones than in the past.
I'm thinking that Texas could provide an example of not taking fed money here. That might not be a bad thing in the long run.