It seems to me this article is a fantasy. A what if scenario. I don't think this guy really knows pacemakers at all frankly. A bluetooth enabled pacemaker seems far fetched and to my knowledge such a thing does not exist. Pacemakers require the reader device to be in contact with the patient directly over the pacemaker, the range is that limited.
I'm assuming no pacemaker owners were harmed in the finding of this vulnerability.