Cleet eventually tells the trio that Micah is hiding out at Mount Hagen and tries to convince them that he is "one of the good guys". John can choose to either hang him or spare him, although sparing Cleet will simply result in him being shot dead by Sadie instead.

What happens when you spare the guy in Red Dead Redemption 2?

Dutch obviously won't protest either way, so it's all up to you. The immediate effect is pretty much the same. If you decide to kill him, Arthur will choke him and leave him in the barn. If you let him go, he'll run away.

Do your choices matter in Red Dead Redemption 2?

Ultimately the decision does not matter. You can either choke the O'Driscoll to death or leave him to freeze in the cold, whatever is best for Arthur's character.