As a serious photographer, and a recent convert to biking, I was also curious about this. I normally shoot with a very large/heavy full-frame Nikon D810 or D800, which I have carried many miles in my backpack to get places you can't get by car (nature/landscape is where I make my money with my camera, hate portrait work). I also do a lot of kayaking, always worry about my $$$$ camera falling in the water, so I bought a much cheaper Nikon D3200 a few years ago to shoot while out on the water. I had the same concerns about vibrations on the bike so started carrying my D3200 in that very same Topeak HB while biking, several thousand miles later I have never had an issue. I tossed a few micro-fiber towels in the bag with it, some for cushion and also to keep my hands clean. Salty sweat from your hands will do more damage than vibrations.

Most modern cameras are tougher than you think, lack of use kills more of them than abuse. If you think about putting your camera in a backpack that gets set in the back of your vehicle it gets a lot of vibrations, as well as airplanes and just walking. I may eventually destroy this camera from vibrations but I would rather do that than leave it at home. A camera is only a camera when out shooting photos, otherwise it's just a paperweight at home.