There's no math involved. He was running late and would have been 14 minutes, 45 seconds late anyway, and a bike slowed him down by 15 seconds, so it's the bike's fault he's late.

A single car waiting to turn left on a 2 lane road can easily slow you down more than coming upon a dozen bikes, yet nobody says that we should ban left turns and instead make everyone go around the block to turn right.