I will readily admit that I don't like suicidal Monty headcanons just because that shit brings me down and I have already been in so many fandoms about suicidal dudes. But the real issue I have is:
I don't think some of y'all have ever known someone who was immortal.
Obviously Monty is not literally immortal, which we know from the fact he's been dead for 40 years. But sometimes in your life, you will just know someone who is immortal. This person fears neither death nor man, and they will just do shit because ain't nothin killed em yet. The balance of the evidence so far suggests that they will never die, and they bend the universe around them due to the gravity wells created where their ability to appropriately respond to danger is supposed to be. You just get pulled into their orbit, and hopefully you live to tell the tale.
I cannot express to you how much I am not describing a character archetype; I am describing a kind of real person. Unfortunately for my parents, my brother is immortal, and so was my uncle. One time, in about 1973, my uncle and my parents were at a show in Tuscaloosa, Alabama; he walked up to them and told them some guys had invited him to go to Atlanta to see another show. And by that he meant he was getting in the car with them right then, and he'd see them back home. By the highways that were constructed at the time, Atlanta was nearly 250 miles away from Tuscaloosa, and home was even further away. He just wandered off with the clothes on his back and like $25 with complete strangers and not even a phone number where he could be reached. It wasn't even the weekend. This happened on like a Tuesday night.
He turned back up like a week later with stories about how it was the best concert ever, because that is what being immortal is about. It's like having plot armor in real life, and that is what Monty has going on. He's reckless because he cannot be killed, and this is pretty much what happened to the actual Ewen Montagu as well, who suffered things that should have killed him multiple times. Hitler could have come to MI5 to take him out personally and the fuckin gun would have jammed, because he was too powerful, and musical Monty is even more powerful.
This fully does look like passive suicidality, because that also makes you unafraid of death. However, people who are immortal are having a good time doing it. The people around them? Not so much. This is the same uncle who liked quaaludes a lot and once necessitated my parents having to dispose of an entire garbage bag full of marijuana. (Again, it was the seventies, that was probably about $6.50 worth of weed.) People who are immortal tend to believe that everyone around them is also immortal, and that is incorrect. Some of us live by the rules of the real world, and the plot armor extended by someone who is immortal wears off very quickly. We don't all get to be Bugs Bunny.
All of this doesn't even touch the fact that Monty needed to live to spite all the people who wanted him dead, and it sure wasn't just the fuckin Nazis. There are antisemitic conspiracy theories about his family in specific that were being passed around before he was even born. He could have been hit by a bomb- physically crushed under it just before it exploded- and he would have got up and walked it off, because no one was allowed to kill him, not even Monty.
Anyway thank you for coming to my TED Talk, there's cookies in the lobby and I will be signing books. BYOB, I've never published anything