Wow! Seems rather harsh to me. I would never bump someone on purpose because I felt I was right.I ride the "Galloping Goose" trail in Victoria, BC quite a bit, and I'm one of only a few cyclists with a bell mounted (it's attached to the pump, like the amateur racers do in Belgium where I think bells are required by law). I'll usually use the bell when approaching peds from behind. I whistle thru my teeth (a technique I learned in Mexico where cyclists whistle at drivers to announce their presence) when approaching slower cyclists from behind (louder than the bell but a more piercing sound). I think the advantage of a bell is that it's non-intimidating. It's like dainty Tinkerbell is behind you. It merely announces your presence. A car horn, on the other hand, is objectionable because its message is "get the #%$ out of my way!" I have acually been thanked on occasion for using the bell. More often, though, peds will just keep walking straight, or make like they haven't heard the bell, especially if they are two abreast blocking half the path.
I think a big problem is just plain arrogance. Each MUP user is loathe to acknowledge that they need to "get out of anyone's way." They see it as a sign of weakness, as forelock-tugging. The worst are two or three females that block the path. They are usually so arrogant or condescending theyll move over for no one. Likely a product of our cultural times, where everybody thinks he's a celebrity, "king/queen of the world." You see less and less courtesy these days in impersonal places like MUPs.
The only guys who pass me are wannabe racers who are out to prove something (I'm usually travelling at around 30 kmh, which I think is the highest speed reasonable on a MUP - quick but I'm not making any kind of effort, and I'm able to respond/slow down quickly). I can usually hear tire noise coming up behind me (plus I look around quite a bit). But I'm usually positioned towards the right side of the lane anyway, so it's never a big issue.
With cyclists, the guys that bother me are the ones I'm about to pass who pull out without looking to pass even slower riders ahead of them. If I have whistled or otherwise announced my presence, then I think it's fair game to buzz or bump them. Usually in a bike/bike collision, it's the guy being overtaken who goes down, so it doesn't bother me (especially if I'm in a foul competitive mood), plus I've had about 35 years of bike racing experience, so I can handle bumps. I even practice bumping against the rails of bike bridges if they extend out like the balustrade around a velodrome. It makes you a better bike handler and able to absorb bumping in a pack.
People with dogs are usually the most appreciative of the bell; however, I wish they would learn to walk on MUPs with themselves between the dogs and the bike traffic. If you ever visit a stable where they keep racehorses, you're always cautioned to make sure that when you are passing by a horse and trainer, you should always have the trainer between you and the horse. I wish more dog owners would learn this...