I sincerely doubt they would kill Warmachine in a non-Iron Man movie.
Second, there is the optics around the Trope in question.
Hawkeye's support of Bucky would mirror his support for Natasha who also used to be a Soviet/Russian spy/assassin. Maybe he's a fan of redemption?
There really isn't a good solution to the question of super powered individuals. Vigilantism can't be tolerated, but governments can't be trusted.