First off you initiate on him on the roof, leaving yourself exposed with no real hostage, if the hostage ran behind that would he would of not been you're hostage. the guy who counter initiated wasn't even in a gang, and simple was trying to help out another civ, you played that situation bad, there are things in-game to help this, such as zip ties, blind folds, lock picks... the guy that told you to put you're hands up was behind a wall when he initiated he also doesn't have to value a hostages life as hes not a cop.
If you ask me this was poor role-play if you're trying to steal his car why is he you're hostage. like role-play say "I'm searching you for keys!..." "i found the keys in the right left pocket"