I have been buying motorcycles for 56 years and I think I have developed some thoughts about what it takes to sell motorcycles and stay in business while doing so. Plus, I have spent some time during recent years talking to the owner of the BMW shop that I frequent. Motorcycle dealerships don't make much money just selling "units". As an example, recently I was told that KTM dealers only make $400 profit on each KTM 390 Duke that they sell. Larger bikes pull in more money of course, but it costs a huge amount to keep a motorcycle shop open every month, thanks to salaries, property rent, paying taxes and various fees, complying with government and franchise regulations and a lot of other "overhead" stuff that is not so obvious to anyone but the owner and their bookkeeper. Just selling bikes is not going to be enough to keep the doors open without some additional sources of income.
So where does the money come from to keep a motorcycle business open? Profit selling the "units" is certainly a part of it, but the shop has to split the profit with their sales staff, who works (at least partially) on commission. Sales of parts and accessories used to bring in some decent money, but now with internet sales of just about everything, not so much anymore. The real steady "cash cow" is the service department, sometimes referred to as the "backroom". Motorcycle dealers in the SF Bay Area typically charge about $130 an hour for their mechanics' labor. My understanding is that money typically gets split about 50/50 between the shop owner and the technician. If they can keep service customers coming in nonstop, which is what happens at most shops in California (just try to get a service appointment within a few days of your request). I can't recall seeing any service department technicians standing around doing nothing - except maybe the service "advisors". So service departments are the only real source of steady income for a motorcycle shop and they need to make the most of it. Therefore I doubt any dealership would want to discourage anyone from bring in their motorcycle for service or repair - even a Zero. And if they do, they are just shooting themselves and their profit margin in the foot.