That's the sort of dickishness that makes us all look bad. I see near misses by cyclists like that nearly every time I ride the MUP (which is less often all the time -- I use the MUP only when it's the most expedient route, not the fastest). Brush-by passes at 15-20 mph inches away from pedestrians and other cyclists.
Much of our MUP is only a 4 foot wide sidewalk, just suitable for casual cyclists who can barely cope with safely passing people traveling a single direction, let alone oncoming traffic. It's a sidewalk. It's not a proper multi-use path for cyclists. We expect a 3 foot buffer from vehicles on the streets, but cannot practice the same courtesy toward pedestrians on a 4' wide sidewalk/MUP. The best we can do is slow down and pass just slightly faster than walking or jogging pace.
Occasionally I see older folks on canes, walkers, in wheelchairs and riding pedicabs. Frankly I'd advise against using the MUP to my older family members and friends. It isn't safe, especially for folks with balance problems who are easily startled. It's absolutely no different from sharing a city sidewalk with kids on skateboards, inline skaters and bicycles, which is usually prohibited. If anything our typical city sidewalks are wider and more navigable than most of the MUP.