The account has little basis in reality for several reasons. The first one is that the voltage and energy needed to brdige from powerlines to the ground is immense and likely not the be carried in the lines. In the event that there is enough and for some reason a shock will come out, it makes much more sense that the bolt will spark from wire to tower to get to the ground (always takes path of least resistance). Also, there is no direct ground connection on the bike, the wheels are made of rubber. This is why you are not really at risk in a car.

I personally, knowing a lot about electricty (through engineering studies) find this account to be extremely unlikely and suspect that there must be another explanation, futher tests need to be done to prove anything conclusivly. Either way, it surely isn't the bike manufacturer's fault.