A statistical result like that is usually only the beginning. It points toward interesting questions revolving around "why".
Whether or not BMI is a flawed metric for being "unhealthy", it's a concrete metric for an aspect of "size". The correlation the study found was strong, but that just opens the door for specifying a better metric for the various factors that go into "size" and how they could be a cause for this-or-that outcome.
Re-doing the study for shoulder injuries (DL/IL time, etc) might also be illuminating. If UCL correlates in a way rotator cuffs don't, wouldn't that be interesting? Chris Sale and Alex Meyer have shoulder troubles, Micheal Pineda has UCL ... one can go back and forth with anecdotal evidence, which is why the structure of a statistical analysis should be better.
I'd be surprised if teams weren't already on top of this, but it was interesting to see it come from someone so far outside the mainstream. Part of the point is that the data is out there, so that even a bright high-schooler with good mentoring can tackle it. So, why* haven't I?
Anyway, this prospect fits a profile that used to be considered a better risk because of a sturdy build, and perhaps that opinion will abruptly shift. For all I know, the Twins were able to sign him in 2017 because other teams were already 2 years ahead of them in this bit of analytical insight (assuming it is solid).