There are a lot of things at a hotel that guests are allowed to use as part of the price of the room but most people never actually use them. How is this any different?
I would expect any Tesla contribution to these won't include charging other brands of cars for free.
That’s not exactly how it works. Their Destination Charging program mostly uses non-networked Wall Connectors and the press release says it’s the Universal Wall Connector with the built in J1772 adapter.
It might be possible to install access controls on Wall Connectors, but would probably defeat the purpose of the Universal version. It only works to allow Teslas by VIN/name. It can be set up via Wi-Fi but doesn’t necessarily have to connect to anything else other than for setup or for firmware updates.
https://www.tesla.com/support/charging/wall-connector/access-control