How can I get the shop worker's luxuries need met?

You need to engineer a situation where your malcontent is indisposed and another prisoner claims the job first. The game is not great at micromanaging like this, so creativity is required.

Prisoners claim a job at the beginning of a work timeslot, then start pathing to it to start work. The reason removing the position and reopening it doesn't work is because your malcontent is still around to reserve the slot.

I see two possibilities:

• Punish your malcontent (call it "bad customer service", likely it's true). If he's locked in his cell or solitary, he can't start work. Time it so that he's locked up at start of shift, and gets released while someone else is working the store. So long as he doesn't immediately claim some other job, he should treat the workshift as freetime and resolve his need accordingly.
• Set up a second backup store. If your malcontent is manning the first store, he can't claim the job at the second. You can then force him out of the first store by removing his position. Then he can resolve his need at the second store.

This is all presuming there aren't any other problems, like lack of anyone else qualified, your prisoner shanking the new store keep, etc.

Contraband luxuries would also satisfy the need, but obviously the less of that you have the better. I've also seen mention that if cell grading is enabled, higher quality cells will satisfy this need, but as far as I can tell, cell grading only affects behavior and probability for misbehaving, not any of the needs.