Just about any store in the USA can ban customers for non-discriminatory reasons. For example, if you go to a restaurant, start swearing at the servers, throwing your food, and misbehaving, you'll quickly find yourself banned from the location.
I think it varies by state, but as long as the banning isn't because you're part of a protected class[1], a private establishment can refuse service for any reason it sees fit, including none at all.
Ah, yes, that's what I meant by most cases. If you establish rules that do not discard a class of the population, then it's very much acceptable to reject those who infringe them, in my opinion.
In any case, I was just correcting your analogy, not your premise.
Right, and banning a customer from a store is equivalent to a computer denying a request from a remote client. But in this case, the computer didn't deny the request.
No, banning a customer is almost exactly equivalent to sending the sort of C&D letter that Craigslist sent. I'm banned from Walmart for life, and was asked to sign a trespass warning explaining that if I'm found on Walmart property, I'll be charged with trespassing. That's Walmart's right.
Just because the door is open doesn't mean that everyone is welcome to go through it. The same holds true for websites just as it holds true for grocery stores.
I think it varies by state, but as long as the banning isn't because you're part of a protected class[1], a private establishment can refuse service for any reason it sees fit, including none at all.
[1]http://en.wikipedia.org/wiki/Protected_class