Not a contractor. To me it makes no sense. Depending on the cabinet design it may make very little difference. Do the cabinets go to the ceiling? The contractor may not want to patch and paint ceilings that won’t be seen. The thing is, that’s a little ridiculous. What if he gets paint on the cabinets because he painted the ceiling afterward?

Not your battle to fight but it does seem odd… when you say ‘plaster’ are you talking about a texture coat on drywall or?

He is installing the cabinets? I wouldn't die on this hill. You don't have enough info to ascertain why? Something unusual about the cabinet style? The ceiling height? He doesn't know how to scribe a trim? The house is old, not level?

Doesn't sound like a great idea. Yes the new cabinets will need to be covered. But? It's not your kitchen : )

STOP now and get a new guy or at least insist this ceiling is finished before cabinet install This is amess waiting to happen and for no reason I can think of.

Thanks for the clarification. I mean you could do it this way but why? I’d want it finished so there aren’t open joints for dust and bugs.