No, anyone can set up a server on appspot and do this with Google.
The only cooperation needed from the host is apathy. They could take direct action to stop it working (Cloudflare did this a few years back by requiring that SNI matches the host header) or suspend the server running the reflector (Google did this to the meek reflector running on Appspot that Tor Browser used).
The only cooperation needed from the host is apathy. They could take direct action to stop it working (Cloudflare did this a few years back by requiring that SNI matches the host header) or suspend the server running the reflector (Google did this to the meek reflector running on Appspot that Tor Browser used).