I agree it shouldn't be relied upon as a troubleshooting step (you need to know what broke, why, and why it won't happen again). That said, if you go years without rebooting a machine... there is a good chance that if you ever do (to replace hardware for instance) it won't come back up without issue. Verifying that the system still boots correctly is imo a good idea.
This doesn't contradict his advice, as you're suggesting to reboot every few months when the machine is working. His advice is to not use a reboot as the first step in solving a problem. If anything, a periodic reboot when it's working is probably in-line with his advice, as it's a way to uncover more problems that may be lurking, at a time when things seem to be working (and hopefully when the downtime won't be a big issue, like during low load).
Now Stupid Coworker knows that it was me that reported him for sending me porn.
...because your boss is a dork. He should have send a message to Johnny Five (or everyone), "reminder: don't send porn to co-workers".