Similar thing happened to me on returning a rich tourist BACK to the station, a station and faction that I'm allied with!
The station allowed me docking access and as soon as I was passing through the letterbox all hell broke lose, and I was left with my mouth hanging open staring at the rebuy screen.
I checked the passengers credentials before accepting the mission and found no evidence or indication of illegal shennanigan's, Just 3 Rich Tourists sight seeing.
BTW I accepted the mission through the same faction and station I'm allied with.
I'm putting this down as a bug and will be forwarding it to support.
Same here. So, i learned my lesson and made a cheap passenger ship (rebuy cost < 110k). It's not a big loss when such a thing happens.