Re: If not prohibited then its permitted?
"How are we to apply this to detached garages, tool sheds and other accessory buildings?"
These are not "fire rated assemblies".
Fire rated Assemblies are not the space, but the construction. For single family and 1 & 2 family dwellings, detached garages, sheds and most other accessory buildings are not fire rated at all.
In single family dwellings, most likely the only fire rated assemblies will be associated with the wall between living space and the garage, and the walls around a furnace room (not furnace area).
334.12(1) tells me that Types I & II are not specifically mentioned in 334.10 (1), (2) or (3) so those Types of building construction no matter why they are installed shall not have NM cable installed.
The language may not be what we would like, but it is there.