Well, it appears to be over zealous management. One might as well say “eating at your desk can get you fired”. The problem isn’t the eating. It’s the management.
One of the few comments in this thread that isn't rooted in Stockholm syndrome. Sure, it's prudent to do one's personal computing on personal devices - get a personal laptop or a GPD pocket or something like it for use at work, and only use their uplink via a wireguard link to something else you control (and/or get a cell modem). But management that fires people for using a protocol, and furthermore for using it incidentally? It makes me want to publish everything I do as onion only.