All good points for the prospective starship thief.
Still you need someone to keep all those bounty hunting adventurers in work, no criminals to chase, no rewards to collect.
As regards deposits for ships and the like. Asking for a large deposit rules out players owning ships unless they have the odd Mcr10 lying around.
Far more likely they will background check the people involved. Retired merchant captain, getting a used ship through a well known trade line. Been working the sector 20 years, plenty of recomendations and character witnessess. Sign here sir.
Off the street adventurer, not known, flagged by local law enforcement for borderline activities, known assocoiate of criminals etc. Don't let the door hit you on the way out.
With it being easy to steal a ship and flee across the borders and with the lack of high speed comunication of traveller banks etc are going to check very carefully who they lend money too but they still lend money and insure it against loss.
Anyway why would the sword worlders want a stolen Imperial ship, its not like they are big enough to hide it.
The doggies would be more likely to do a deal but then they may just as well do the deal then sell the location of the shipjacker to the bounty hunters. Plus of course do this enough to get noticedand the local clan gets a visit from the hugely overstrength corridor fleet who pop in to say hi and for a few years after this the nearby clans are reluctant to handle stolen Imperial ships.
So sure with planning you can steal a ship, then what, retire on the money. Your traveller life in the Imperium just died, you could spend the rest of your life in the extents but even so steal a ship from one person, sell it to another and no one will trust you with a ship again.