If it turns out they are fractional? Then I would frown on it. But if they are actually custodying BTC then yeah... doing something small to help make them successful is not a bad idea.
And if they chose to have a fractional BTC reserve? It would very possibly be their undoing.
They have a Bitlicense, which requires 100% reserves. Not a
guarantee of anything obviously, but they appear to be doing everything
very by the book. I'd be much more worried about a hack than intentional fractional reserve.
Honestly, it's pretty cool to see "Your crypto" in my Paypal dashboard. Not cool enough that I'm going to load up my Paypal account, but if I ever have some cash on there, I'll buy some Bitcoin IOUs.