It's one time I'm glad I was unarmed. I would like to hear what anyone who disagreed with me writing the letter would have done, particularly if they had been armed at the time they were threatened (unintentionally or not, which is debatable). This is also kind of a "Strategies and Tactics" topic because we all have to balance our reflexes against the possibility (however slight) of being menaced by a fake gun by someone who is...I don't know, young, or mentally deficient, or whatever the guy who did it to me was.
As far as the "threatening" part of the letter, I think I did a good job of keeping that low-key in this context. I am fairly confident that this college will not take the prof's side to the point of trying to get me in trouble. I am starting to think he may be pulling a card like that as he hasn't responded and he read it at 8 pm last night, but I am not worried. I didn't do anything wrong, and I also said (in essence) that the purpose of the letter was to get an apology and make sure he didn't abuse his privilege as teacher any more. I think most people would agree that my assessment about undercover agents or ex-military is accurate, and thus it's more a statement of fact than a threat. I didn't go into any great detail, and I pointed out that it would be tragic if anyone had gotten hurt. I even went so far as to say that any personal embarrassment on my part was beside the point.