I've accidentally hit an out player a time or two, usually that was because they were out but didn't have a hand or gun up and I didn't see their barrel bag. Honest mistake, though I also didn't put a rope onto them, just a couple shots.
In the same regard, I can let a couple stray shots go on my way out, but someone putting a rope into me would piss me off and I'd be looking for a ref. That type of behavior should result in the ref punching their player card at a game. If it's walk on, they should be warned and then removed if it remains an issue. "It happens" is not an acceptable or valid excuse.
Team Trigger Happy