I think many people equate MUPs with sidewalks. While they would never just stand in the middle of the street, they will stand in the middle of MUP and assume that anything coming toward them will be moving slowly and/or go around them.

They'll also walk across without looking to see what's coming. Just something we need to be aware of as cyclists. It's like when I see a squirrel on the side of the road. There are rules, but it would be dangerous to assume that the squirrel's going to know what they are and follow them.

There are a couple of blind curves on a MUP I sometimes take part of the way home. This was a good reminder to me to take them slowly.

Just as an aside. I know of fellow cyclists even that get annoyed when roadies choose the road instead of a MUP running parallel to it. This is exactly why they do.