It would be hard living in such a beautiful spot if there were bikes going by from sunrise to sunset. Throwing stuff is probably by people who are at their wits end. The solutions at both extremes aren't reasonable: crackdown on bikes vs. free for all. In terms of who has the power in the situation, it costs them nothing to have cops sit there all day and collect revenue for the province.
The main question is how to make it worth the locals while to tolerate bikes and the culture that comes with it. Locals vs. tourists is an issue everywhere, and the most reliable way to resolve it is to make it profitable. Everybody moans about their customers, but the reality is that the forks is getting too popular to be free.
What do people do for a living up there anyway? You'd think some kids would have set up a shop doing detailing and oil changes and some while-u-wait services. Every person who rides through there has $20 or more in their pocket to spend, and it's the locals fault if they can't figure out a way to take it. If the best they can do is let the province collect it in fines, then it's their loss.
The mayor of Belfountain should check out Deals Gap and figure out how to profit from the attention.