I'm not saying it's a good system, or that I endorse it at all. I'm just saying that this is how the system behaves, given what we know from the rules.
There is nothing in the book tying a Persona to a SIN. There is nothing tying a Persona to a device. Yes, there are thematic appearances based on the item you're using, but that just means the default avatar looks like a pirate or whatever. You can use Change Icon to alter that whenever you want. But the appearance of your Persona is irrelevant.
What we do know, is that Ownership (capital O) of devices is associated with your Persona. If someone steals your car, with your Commlink in the passenger seat, you can go into your office or the nearest public library, and log into the Matrix. You will log in with YOUR Persona, which will automatically be able to claim 4 Marks on both the car and the Commlink since you are the Owner of those devices. Then you will be able to Trace Icon on both, giving the authorities the location of your stolen property. Or you could simply Control Device on the car, forcing it to pull over and shut off. Heck, if you don't mind the mess, you could drive it into a brick wall and rapidly vacate the driver's seat.
So like I said, the idea of what a Persona really "is" and how it really works, seems to have been left purposely vague and nebulous. Kinda like how Hosts were some ominous, unknown "thing" that defied normal Matrix definition. And now that we've heard about the cloud computing and the underlying Foundation dreamscape... I kinda wish they would have just done some sensible stuff instead.
Go ahead and tie the Persona to the SIN. That way if you get Converged, you have to burn the SIN and get another. That identity is gone, reported for being a hacker.
Go ahead and call a Host a server. Give it a mainframe in a basement somewhere, with an antenna powerful enough to reach anywhere (thereby justifying the no-distance rules) but let it be a device instead of bogus cloud nonsense. Then hackers can hack it just like a device should, and Technomancers won't be completely useless since it's mystically impervious to Resonance (even though the Foundation sounds exactly like Resonance and TMs should be Gods in there).