It’s that when you have legal agreements with guilds and unions, even produced promotional material can be considered a production requiring minimum staff (I.e. makeup, camera technician, etc.) On productions, any person wearing multiple hats is tightly controlled.

A cartoon I watched growing up ran into this when they needed to insert live action, so they deliberately recorded at 1 FPS for that episode to make it ineligible for budget reasons (https://phineasandferb.fandom.com/wiki/Tri-Stone_Area).

If you’re ever wondering why a company can’t do something simple and obvious, it’s probably due to a legal agreement.