I had something like that happen on the local MUP where there's a narrow bridge crossing. Some kids had stopped where you transition on/off the bridge to look down into the small stream below and were un-noticable as you approached. A older guy (relatively speaking as I'm 65!) in front of me stopped suddenly because of the kids, I veered off to the side a little to miss him as I stopped, and I said I was sorry. He proceeded to go into a tirade about how evil and dangerous I was. When we got to the other side of the bridge and back on the trail he kept at it, riding right behind me and letting out a string of verbal epitaphs of how evil I was as other people were riding/walking by. I got off the trail ASAP to see if he would follow; he didn't. I wonder how the two others riding with him put up with that if its his normal mode of behavior on a fairly busy MUP trail. I still ride that MUP regularly and have never seen him again (thankfully).