The embargo might have ended, but perhaps all of the details are not yet in place to make it practical. Customs forms need to be reprinted (whether paper or electronic). Are UPS and other carriers ready to go? And so on. An entire generation of US businesses and people have never done business with Cuba, that isn't going to change overnight...or even in a few months.

Or maybe the Pebble founders just don't like Fidel.

The Cuba embargo has not been lifted, restrictions have just been loosened a bit.

They might have finalized the copy before that.