clambering up on soapbox/
No internet hoax, entirely plausible. So two steps might have prevented this.
Firstly, some (all?) DCC systems allow you to turn off track power without shutting off the power to the system. He may not have appreciated the difference, but it quite likely would have prevented this.
Secondly, it is only common sense to turn the whole system off when not in use. Do you leave your range elements on all the time? It's tedious to run around to all the boosters, power supplies, etc. to shut them off, though. For some systems, turning it all back on needs to be sequenced, complicating the issue as well.
When I (re) built my layout room, I fed all plug circuits from a set of switches at the entry. All switches must be off whenever the layout room is not in use. I've never had a problem with the DCC system on start up (though this reminds me, I'm due for a battery change in my control and booster units!). Not only do I remove risk from the DCC system, I remove risk from just about everything in the room - soldering irons being the other major fire hazard. The only things left powered are the dehumidifier, emergency light, and the sump pump.
Remember, you and your family generally sleep right above your layout. For peace of mind, it's the only way to go.
Maybe WiringForDCC should have a page on layout safety and pre-build design considerations?