i've reacted both ways. one time i just waved, and the next i followed them into the gas station they almost right-hooked me going into and confronted them to explain exactly what kind of screw up they were and my condolences for them being the product of siblings.

but, maybe i'm in a unique situation as the police here make it known that they don't care about cyclists. we're on our own. doubly frustrating as i used to be a state LEO.

(in NY there's no 3' rule, just "safe distance". which, to my jaded legal mind means "what? i didn't hit him did I?")