I still can't work out how Finney would eventual ever get off the ship
It seems that the transporter can be operated so that a single person first sets a destination, then sets a delay, and then climbs onto the platform. Didn't Lazarus do that a lot? Finney could transport down whenever he wanted, since transporter rooms are apparently rather seldom crewed yet still always at hot standby. He could skulk to one of the cargo units on the lower decks (say, the one that allowed van Gelder to infiltrate Deck 14) when the ship is visiting a planet where Finney's face isn't too well known. And he could program the computer to forget all about the transport...