But then if Data wasn't the property of Starfleet, then neither was Lore.
That doesn't follow. Data, specifically, was deemed by a Starfleet hearing to not be property. Lore was not.
The rights extended to Data on that occasion do not automatically pass on to other androids or computer systems.
However, I would like to think that he got a fair trial at some point. I'd also strongly argue that he is not unimprisonable (is that word?), just because he's clever/strong/fast. He's just as physically capable as Data, who had been previously imprisoned by a mere collector with a forcefield and strong door. Lore would have no chance of escape up against Starfleet's finest prisons, and that's even assuming they gave him his body.