The rule they should enforce is to make sure that any personal heaters are equipped with overheat sensors and "tip switches," so they shut off at a safe temp if someone kicks their "snack bag" where it blocks the heat output, or if they're accidentally tipped over.
The simple phrase "space heater" spoken softly in a quiet barroom will immediately identify all the firepersons present, by the spilled drinks and nervous fidgeting that ensues.