Threatening to essentially abandon US citizens after a natural disaster? Unheard of. This shit-show just gets more embarrassing every day.
Unfortunately, he is between the proverbial rock and a hard place, and the liberal mayor of San Juan knows it. Failure to give aid will make him appear to have refused it to "hispanics" and the Libs will make political hay of that despite much of the situation there being due to mismanagement by those same liberals.
He would do best to work with (as much as possible) those who will work with him to address the issues the Island has, rather than those who have mismanaged things. Trying to restore the failing infrastructure to where it was before the hurricanes makes little sense: it likely would have failed (what wasn't already failing) without the storms. So rebuilding it better is the only real option for a long term solution, and that is going to take money.
Unfortunately, that takes determination to do the right thing, even for people whose government may not deserve it, and do it well, as a matter of
principle. After all, we're Americans, and if we can do this for people in other countries, we can do it for our own.
In the meantime, the corruption and/or misfeasance in Puerto Rico should be exposed, and the people there informed that that is the real source of their problems, not the government on the mainland.