Or maybe make it automatic hostility after 2 seconds, they could shoot you during the the time of you having to hold down L2, then hold down the button for feeling threatened spin counter is done. And then they could be all "I'm offended you did that, i was never going to shoot you, now I have the right to attack you!" BS argument.
As some have stated, aiming at someone, you should automatically be considered hostile. But they don't put into consideration accidental snap aiming and that shouldn't make you as a marked hostile.
But, if someone is going to run around randomly pointing guns at people baiting them to taking shots first, then they should be held accountable for their actions with an automatic hostility after 2 seconds targeting someone.
And also make it so they can't try to trick the system where they tap the button over and over again in less than a one second interval so they don't get marked. Once the first aim, a timer starts so if there's more aiming they get marked hostile.