It's not public in the sense that applies to law enforcement. By that I mean, Noisebridge is a private community that happens to be rather open in terms of membership. "Public space" is more like the sidewalk or a government building.
Note: I'm not a lawyer, but that's my understanding
By similar logic then, you're saying that what Weev did should be punished under CFAA. The AT&T site was "open" in terms of access but it was "private" because AT&T said it was. Picking and choosing what you think is "public" or "private" on an unsecured, open access server/network is a slippery slope...See Weev's prosecution.
Running a Tor node means you're running a public service. Full stop.
Didn't Weev have a legitimate AT&T account? Isn't that how he discovered the vulnerability in the first place? Seems to me that would make him part of the "AT&T community" to whom the site was open to.
But ignoring all that, the definition of what is open to the general citizenry and what is open to the people representing the government are two distinct things.
This is a very recent example where the law is pretty explicit about what the cops can do versus what the public at large can do:
