People seem to be confusing a pacemaker with a defibrillator here.
My wife is on her second pacemaker. The pacemaker sends a very light electrical signal to her heart depending on what the internal microprocessor measures from her heart rhythm. Even she isn't normally aware of when it actually sends out a pulse. About the only restriction on her normal daily activities is reaching above her head or heavy lifting with her left hand and arm.
A neighbor had a defibrillator inserted a number of years ago. When he would have an episode, the result would vary from a sudden tensing of the body similar to somebody giving you a static shock on a carpet to a major convulsion that could knock him off his feet and leave him semi conscious for several minutes. As his condition got worse, these episodes went from less than once a month to several times a day.
His doctor "Strongly Recommended" that he not drive because of the possibility of having an episode while behind the wheel. A neighbor who had a nephew on our local PD asked about it. The law director apparently said that they couldn't take him off the street unless the doctor reported something more definite than a strong reccommendation. He continued to drive. Had a couple close calls because of episodes.
Reading this thread, all I can think is if he had been a flyer, his standing on the flight line, holding a transmitter, even with a spotter, and having a strong enough episode to knock him down. The transmitter goes flying. The plane is no longer under control. Maybe if the transmitter is recovered in time, there might be damage either from hitting the ground or from the strength of the defib charge. I know what an external defib can do to someone touching the recipient during a pulse from my first responder training, and it ain't pretty. It can also damage other electronics the person has in his pockets.
My opinion, is that while there may not be any justification in banning him from flying, the BOD of the club is perfectly reasonable in asking him to fly with a spotter, not to protect him but to protect other members from a flyaway if he does have a trigger event.
By the way, in their infinite wisdom, the local controling medical group, after 10 years of less than 16% heart function before he had the defib for 4 years, finally put him on the heart transplant list, 2 days after he went into terminal coma. One of the cardiologists in the decision process was one of 5 doctors who told my wife she was just a hysterical housewife and gave her loads of free sample Valium.