You are missing one point of the clock mesh. The mesh is only the middle part of the clock tree. This part serves to spread the clock globally on a single metal mesh with zero skew. Then the lower part of the clock tree is built normally and can be gated. This means that you can certainly turn off the clock of quiescent sections of the chip. You will still have to oscillate the mesh, but the registers and detailed distribution can be turned off.
Also you can probably run this mesh off the resonant frequency, but at a power disadvantage. Or you could dynamically vary the L if that was possible.