TLDR, no need to get so scientific about it. I've seen this behavior on (PMCO) flights that were severe clear. With the seat belt light permanently on, the FA's don't need to do service in Y, a minimal service in F, barked at the kettles in Y to stay seated, but we could do cartwheels in the aisles in F.

Why not provide the flight details? Perhaps the pilot will respond with his "rationale"?