That would be my guess admittedly but I suddenly imagined a setup where the laws technically as written didn't account for the body being gained illegally and were more 'once you are uploaded into it it is your and cannot be taken'
It's clearly permissible for an AI to be forced out of their body
temporarily if they are sent to Robot Jail (the body assignment guy
explains that most AIs who wish to be embodied have a body to return to upon release), but I don't know of anything in the comic (post-singularity) that addresses whether an AI could be permanently deprived of the chassis they were in.
But I would think that more broadly this would fall under the general law that says you're not entitled to keep the proceeds of a crime. I'm pretty sure the chassis would be considered legally to be property (usually owned by the AI inhabiting it, but not necessarily so) and could be repossessed like any other property given cause - any other approach raises a host of issues. They might have written in some restrictions but it's highly unlikely it would be "under no circumstances whatsoever".
The large equipment AIs (nuclear reactors, submarines, fighter jets, space stations, etc.) probably would not usually own their chassis (Station might be an exception, given that he seems to own a large amount of E-C stock). Instead these would be owned by the power company or the military or whoever, and AIs would be paid a salary to work in them. Then if they wished to move on from that job, they would go back to being disembodied (or to their previous body if they had one), or to a new body that they would have to buy. An AI that was rich enough could buy its own chassis, as May tried to do, and set up essentially as an independent contractor. But given the fighter jet May wanted to get into cost IIRC $750 million, this is obviously not how most of them operate.
In Roko's case, we know that (before the Crushbot incident) she'd been in the same body since "birth", but seems to have gotten enhancements when she joined the police (which might actually have been when she left the creche, for all we know) - Lemon states that Roko got
extra reinforcement as part of her law enforcement package. So this is probably on a basis along the lines of "we give you this enhancement when you join up and you don't have to pay for it if you stick around for x years". It's not clear how it would be handled for an AI who wanted to join the police but wasn't already embodied. It could be as simple as "you must provide your own body meeting these minimum specifications", or the police might own a number of available bodies that could be handled similarly to the large equipment ones, though they might deduct a fee from your salary if they're providing you a body. Or they might operate a "rent to buy" kind of scheme (and surely there would be third party body shops that offer this sort of service too).
For the smaller (humanoid and down) military chassis like Bubbles and OG Pintsize, it seems less likely that these would be enhanced civilian chassis; they are probably purpose built for military applications. There is obviously some ability to remain in their bodies after being de-weaponised. Whether this is a similar "stay in the military for x years and you can keep the body" deal (possibly with x varying depending on the type of body - Bubbles' is surely more expensive than Pintsize's) is unknown; it might also be that the body is a debt they have to pay off after leaving (probably depreciated depending on how long they were in). Presumably some AIs don't particularly want to keep their military chassis when they leave the military, opting instead for either disembodiment or a standard civilian chassis, but it would be cruel to force those who have become tightly integrated with their bodies out of them. And the military is probably able to afford reasonably generous exit provisions.
To my mind the most unclear aspect of this is how it works when an AI leaves the creche and wants to become embodied. Who pays for the chassis? Do AIs in the creche have their own funds, and if so where do they come from? Does whoever commissioned the AI to be created leave it a nest egg? More fundamentally, why are new AIs ever created, post-AI rights? It makes sense pre-AI rights that you could commission an AI to be constructed, which would then work for you indefinitely. In a post-AI rights world, where an AI once constructed is free to choose its own employment, where's the benefit to anyone in creating one? Do you just hope it has enough of a sense of gratitude to sign up to your service for long enough for you to get some return on investment? That sounds like a very shaky proposition to me and I can't see any organisation going for it - and yet the alternative of "this AI must work for company X for a minimum period of 7 years" is essentially AI slavery, which presumably is no longer allowed.
And yes, you can ask the same question about why people have children, which isn't generally because they're looking for ROI, but the key difference is that AIs are functionally immortal, particularly since they can transfer into more advanced bodies when their current ones become obsolete. That changes pretty much everything.