I think the people in the neighborhood have a legitimate complaint considering it's "open to the public" which is not permitted. Just because you own the land doesn't mean you can do whatever you want with it. That's why we have zoning laws.

But I have to laugh at all of these people indicating they are entitled to this land as some sort of free park, which I assume, was likely private land, not public land before it was purchased by the Soylent guy:

"Residents have long lobbied to keep the rugged hilltop, which is popular with hikers and joggers, a de facto park free of development."

If they want it to be a park, why don't they pool resources together and do that and then set it up as a park? Everybody wants to complain but nobody wants to backup their complaining with their own money.