Just read the comments above, and think about them. The study did not count actual bodies on the ground, or look at how they died. It calculated the total number of deaths in the period under discussion, and compared them to death tolls in the same period in previous years, then classified the discrepancy as "hurricane Maria deaths". It did so without actual, physical evidence that the hurricane or its aftermath had actually caused the deaths in question - it simply assumed that. This was a purely statistical analysis.
Emphasis in the original. And as Peter Grant points out, this comes as Congress is doling out money for hurricane recovery, and Puerto Rico wants it's cash. Of course, this being Puerto Rico, any cash we give them will disappear down a black hole of corruption, graft, greed, stupidity, banality and socialist assholery.
Here's my personal solution: We give Puerto Rico everything they want. Clear the debts. Tabula rosa. And then we tell them "Congratulations, you are your own country now!" and cut them off. Let them do whatever they want to do. Let them be whatever they want to be. But they won't be America's problem any more.