KW> I'm surprised Fidonet didn't specify UTC (or some USA time zone) for KW> all of Fidonet, given the ZMH requirement back before continuous mail KW> was possible.
I will go further than that: the founding fathers made a serious mistake by using local time instead of UTC - or GMT as it was called back then. There has always been a large overlap between the HAM community and the Fidonet community. When I became a HAM in the early sixties of the previous century HAMs already used GMT when logging contacts and exchanging QSL cards. It makes sense when using a medium that does not stop at national borders and time zones.
While it may not have been clear that Fidonet would quickly become a global thing, it would have been clear that it was never limited to one time zone. And while Tom Jennings was not a HAM (AFAIK) my intelligent guess is that by the time Fidonet had reached 50 nodes, about half of the sysops were HAMs and it would not have been too late to make the change from local time to GMT.