We've known that at a lot of Supercharger locations, the signage says something that is not as exclusive, like "30 minute general parking" or things like that, where the business owners can't block off access to those spaces exclusively to Teslas. But in some other locations, it does say "Tesla vehicle charging only", as in this case.
Tesla should have been aware that this is part and parcel of ONE project. At each location where they are opening this up for other brands to use the chargers, they need to send someone with a wrench to remove those signs that explicitly tell people that other brands of cars are NOT allowed to use them. When they opened those locations, they have now made those signs incorrect, and they need to remove them!