good thing you had time to react. In my view, pedestrians and dogs and especially kids always have the right of way regardless and if you are riding a bike on an MUP you need to be going slow enough and paying enough attention to be able to react to anything, and you should always creep by little kids and dogs really slow because they could do anything.
I commute most of the way to work on a couple of MUPs, but if I am out walking, and some cyclist blows past me carelessly I am going to say something, and here in Northern California there are a lot of "entitled" cyclists.