What a wacky thread. There's a reason you're supposed to pull over and stop for emergency vehicles. That's why there are laws mandating it. They are not "open to interpretation".
The idea is to ride in a manner that you never have to direct rude gestures at other drivers. If you get into a situation like that, an upraised finger is a poor defense against a one ton motor vehicle or the loony behind the wheel with a gun who might take exception to your sign language.
You basically created a bad situation and then just made it worse.
