Well the generator idea wouldnt be valid as its connected to the N1 and when you turn the blades you are only turning N2.
Its always a good idea with the Allison engine series to turn the blades backwards to tie the blades down as it helps clean carbon off the knife edge seals in the turbines, unless its locked up which can happen.
Ive never heard of the idea of not turning the TR, but yeah do it gently.