There is no 5 second rule.
The guy was clearly a new player in the cheapest car in the game. They had no bought clothing or backpacks, so there was nothing of value. As a rebel with rebel clothing and a decent gun what was in this for you? There doesn't seem to be any RP intention other than to kill someone and have a bit of fun in doing so, judging by the laughter afterwards this was your intention all along.
it isn't really against the rules. However I just don't see the fun in this? Poor RP and all at the expense of a new player with nothing on them. I bet you just ditched the car or didn't even use it. RP like this ruins aspects of the game.
As a new player learning the controls, 5 seconds isn't a lot when you are panicking and have no idea what's going on.
The laughter at the end was the icing on the cake.