OP, from your description is seems pretty obvious that they were up to no good. I think you did the right thing and I applaud that you were able to keep out of harm's way long enough to get to the safety of witnesses. In my opinion, the actions of those in the vehicle speak for themselves.
Have you considered getting a helmet cam? I wonder what reaction the police would have had they seen for themselves what happened.
Also, I'd keep my cell phone handy if I were you.
This may have been an isolated incident. I hope so.
And good for you to keep riding. Good luck.