Are we taking into account that Miles has beaten (parker) Spider-Man once already?
Peter appeared in a different universe, where everyone knew who he was. That confused him. On top of that he wasn't even serious about fighting Miles and on top of that he would have been able to kill Miles if he wanted, since he easily approached Miles at the beginning.
Kaine would annihilate Miles. It would be a rated M for Mature comic, because of all the blood and gore! Yeah, I love Kaine!