Glad to see some sanity on this issue. Thought he would have been let go for disregarding the rules.
Yes, I figured it would be worthwhile to let people know about this.
It's not clear that the doctor is a hospital employee -- that he's not in private practice or a contractor covering a mental health clinic. IIRC most psychiatrists maintain private practices, and are paid directly by the patient or by their insurers. A psychiatrist might do some mental health clinic work if they have the time. My cousin is a psychiatrist, and did some part time mental health clinic work until his practice became too busy to allow him to spare the time.
In any case, if a physician is self-employed in private practice, he can only be fired by himself. The hospital medical staff rules are unlikely to regulate firearms, beyond indicating that a physician is expected to comply with all laws and government regulations. (Which he did.) He was unlikely to lose his medical staff privileges. Much more likely that he (and the others that disarmed the shooter) will receive an award for courage at the next annual medical staff meeting.
For a non-physician hospital employee, however, arriving at work with a firearm, even if licensed, might not be advisable.