At the end of the day someone is ALWAYS going to do this if you improperly set up rdms. This is the internet, this is why we have mechanics to prevent this. You acknowledge this by saying you expect and allow it for random player constructs "Not every player has your best interest at heart." No matter how much time they spend it's 'well they didn't set up rdms properly, too bad so sad'. Which I'm fine with personally, if you mess up your permissions it's highly likely someone will come by and rob it. You have to own your mistake, learn and move on.
Multiple people seemed to take part over a period of time, some may have taken a few terminals and left the rest. More people came and took more pointless things. Even the person who took the last terminal likely had no clue that it would completely wipe the market from existence. If someone had modified their client in order to do this, sure permanently ban them. In this case some sort of suspension and potential inconvenience at non-player owned markets in the distant future would be more reasonable. Also if this was to happen to a player owned market in the future, I'm sure both parties would be getting a fairly equal amount of hate from anyone who lost resources.
Anyway I'm not sure if player-markets are meant to be robbed as a mechanic, if so the terminals should at least give the thief the current market inventory as opposed to just wiping everything. Preferably (as that would be extremely op), markets should save data, transport unsold goods to the nearest market for pickup by players. Or some sort of mail system in the unlikely event, or just leave a ghost terminal with access to market container after the last terminal has been stolen.
Also if this is a huge issue, structures placed by any staff should always have a flag that overrides rdms and disallows any player from ever picking it up/modifying the construct, why take the risk. A patch for rdms could break something that allows everything to be open season and markets have the most foot traffic. Rdms issues are bound to happen to anyone as we've seen.