I'm kind of the same mindset. Even if the security footage cleared you for protecting someone else eventually, you'd still likely be detained for a while before they officially review the footage and find out this was indeed in someone's defense.
It's a sad system we live in, that you can't even help somebody that truly needs it without going through so much bullshit to do so.
so... you'd allow someone to get beat within an inch of your life because it might cause you a little hassle? seems to me more of the problem is people can't be bothered to be hassled than the sad state of being "detained" for a short period of time while law enforcement figures out what the hell went down.
