I think people have the ethical issue in this case backwards: the reason this guy got this transplant is because it was an experiment. We effectively used an ex-con as a guinea pig. (Personally, I'm fine with that, he was fully aware and consented, it was his only chance.)
If this guy had died due to the experimental heart failing, we'd probably be seeing a bunch of op-eds about our moral failure to prevent exploitation of a vulnerable (ex-)prison population.