I'm not sure what the objection to a motorcycle cover would be, honestly. Most people who park their bikes outside cover them year-round. The covers are much lighter than a tarp, and they're sized to fit a bike, not huge and folded over like a tarp (both of which are to allow air circulation and prevent corrosion). The other thing a cover does is keep condensation from forming on the seat overnight.

The thing you have to worry about with plowing is not parts cracking from exposure (honestly, that's just goofy, a car has an engine and a battery too). You do have to worry about a bike being physically knocked over by plowed snow, and also about exposure to salt contained in the snow. A cover won't protect against the former, but it will give a SMALL bit of assurance against the later.

Really - someone putting a cover on a motorcycle is like someone putting the rag top up on a convertible cage. You wouldn't require a Corvette driver to leave their top down whenever they park it, would you? Again, I don't see the objection. Maybe if he showed the association members a photo of the cover to assure them that it's not some huge blue tarp?