I think the argument is that it acts as a sort of "passive horn". That merely by being near a car you'll be noticed if you have a motorcycle with loud pipes.

It's somewhat true of all ICE motorcycles. They're not silent. But, are they loud enough to wake a driver up out of a daze and cause them to notice the bike?

An electric motorcycle won't be noticed at all through the noise it makes. It might not be that different from a properly silenced ICE bike.

In any case, it's sad that we're in a situation where a driver whose brain isn't engaged with what's going on around him can kill a motorcyclist through inattention.