One flaw in the analogy is that physical space is limited and difficult for a person to move around in. The digital space is effectively infinite, and switching is as easy as typing in a new url (compared to the physical challenge of moving to another state/region).
There are all sorts of flaws in the analogies here; that's why they're analogies, not identities.
That said, I'm not quite sure I understand your point. A speaker in physical space can pretty easily take their speech elsewhere; most obviously to the nearest public street corner. So moving away from a private venue typically does not require anything nearly as drastic as "moving to another state/region".
I'd really like to understand your point and how it applies to both the mall and youtube situations, though, and would appreciate you explaining it if you have the time.
The crux is that digital space is infinite -- anyone can create a space for their own speech. In the physical world, people own very little space, and free speech almost always needs to impose on someone else's property. I think because of that, any comparisons between online speech and IRL speech are inherently flawed and not very useful.
I think there's a difference between "you can speak" and "you can speak in such a way that interested people can hear". The former is not very useful in terms of the right people usually think of as "freedom of speech"; the limiting case of it in the physical world is "you can speak, but only in your own home". So what, if anything, makes for an online version of the public square, where one can go to present speech for consideration by others?
Also, I think online speech is more similar to physical-world speech than you make it out to be. You can't speak online without "imposing" on your hosting provider, their ISP, etc. If you self-host, you "impose" on your own ISP (and probably violate their ToS, if you have a residential connection). You "impose" on your domain registrar. These are all private entities, so you have the same sorts of issues as you allude to for the physical world. And these private entities have been known to restrict the speech of people relying on their services, so this is not a hypothetical risk.
Telling a silenced victim that they can easily move to somewhere else in digital space is of little comfort when their complaint is that they are being denied access to a public audience who are habitually congregating in an existing location.
The extent to which someone is entitled to an audience is of course more difficult to judge.
I disagree with your last sentence; I don't think anyone is entitled to an audience, so it's not a very difficult situation to judge. Free speech means you can shout in the wind all day long.
