This is a touchy one, but I'm not going to side with you just because of what happened to your father. Should this person have flipped out on you? Probably not. But I also know a lot of drivers assume that treating motorcycles like other vehicles on the road is appropriate when in reality it's not. In reality it sucks to get rear ended on a motorcycle. In reality most people tailgate less than a cars length. In reality and being totally honest, this person probably had a bad day, and has had a recent wreck, and you were probably closer than you thought.

They recommend vehicles allow for extra space, similar to the recommendation of more space between passenger vehicles and transit buses, construction vehicles, emergency vehicles, etc. But guess what, 99% of the population completely ignore the words that are written in the driving manual and they tailgate anyways. It's about visibility. A bus driver can't see you with a standard vehicle space between. Nor can a motorcycle. You should learn up on that.

3 second rule for following motorcycles.