The trasmitter's output was below 1/10th watt. So, pacemakers are that sensitive to low power transmitters? Must be hell for you around all those cell phone users in public.
My high school electronics teach was ex-navy (career man), very by the rules, strict as hell on safety issues in his shop. I doubt very seriously he would have allowed anything remotely dangerous or illegal.
The same circuit is availiable as a kit, from many online sourses, which would lend me to believe its legal and safe to use.
Back to the origional post...
Don't think it could work. 7404 is TTL, wouldn't 9 volts kill it? I'm guess it's wired as an oscillator, but seems like its a little light on parts. Every transmitter circuit I've seen (not a field of huge interest to me), has an inductor, usually a small hand-wound coil, just a few turns.
I don't know about pacemakers, but I can't imagine they are so sensitive to interference. There is a lot of strong electro-magnetic energy about, much more common and powerful than what could be produced by a 9 volt battery.
Must be a huge 'avoid a all cost...' list for pacemaker recipients, not to mention all the exercise, diet, and lifestyle do's and don'ts. Trying to avoid everything bad, and remembering to follow all those recomondations, remebering which medication at which time, with/without food... Wouldn't all that stress kill you anyway?