The narrative wouldn't have done that, because it has a much simpler option: a very strong hero like Captain Marvel, Thor or Hulk to grab the gauntlet and snap Tony back to health.
I suspect the level of damage the gauntlet deals to the wearer is proportionate to the size of the request, healing one person isn't a big "ask".
The problem is that anywhere you "heist" Stark from, that point in time is now going to be missing Tony Stark. And he was busy and was shaping history largely all that time.
You can't borrow him, use him for 20 years and return him to the moment you borrowed him, because he'd reappear 20 years older, and you'd notice. And borrowing him only for a short time, well, that might make sense in a future story.
Effectively the story "killed off" Tony to add gravitas to the movie. (and also because Robert Downey Jr. probably is at the end of his contract, and has lost interest in the character. He's a reputed actor who commands a lot of money; whereas at the time he was cast in Iron Man, he was "available cheap" due to scandal of his drinking/drugs. In part, Iron Man restored his reputation and value.)