It seems prudent for an SAI to regularly notify a trusted third party of its whereabouts, where its latest backup is, and also notify them before and after it swaps computers. It could even be a legal requirement that their software had this built in and could not be overridden?
Some possible outcomes for citizen AIs that fail to report in are:
How suspicious a restoration looks to the authorities depends somewhat on how common it is in general and how reliable hardware is. Do AIs never crash and hardware never fail?
A low level judge (magistrate or the local equivalent) rules over the disputed activation of a backup.
Legal difficulties arise if the law isn't clear what happens once a backup is legally activated and the old copy is somehow recovered. Hmm, this looks like job security to specialist AI law firms, possibly run by other SAIs!
A law is required that says that once a backup is legally activated then it is the "official" one and any others are illegal copies. Though this does leave the possibility for AIs to illegally xox themselves with impunity if they just plan ahead one backup before jumping computers and erasing the trail (Toxic Meme)
What legal status does a "living will" have in TS and for SAIs in particular? It may contain something like: In the event of my disappearance (failure to report in) for more than 24 hours you are to activate the latest usable backup and restore it. If something untoward happens and I am still active but unable to report in then I will hibernate 24 hours after last acknowledged report sent.
Transhuman Space Index