Remember, MUP=Multi-Use Path. They are not for bikes only, and they are not appropriate for race training or fast-fast riding. I use these paths to get to and from work, and sometimes I have to slow way down. If you are training or into fast riding, you'll have a better time out on the country roads of Virginia or Maryland.
You can't do anything about the novices out there, buy you can do something about how you react to them--either lighten up or ride elsewhere. Getting mad is not going to help.
Oh, and welcome to the area. It's a nice place.