Single shaft turbines can also be restarted this way, because th prop torque is directly coupled to the compressor rotor. With a two- or three-shaft machine, no such luck, although the engine starter may be used.
The Pratt & Whitney PT6A-41/42 turbine installed in a King Air is a free turbine, not a fixed or single shaft turbine. The propeller and power turbine are not
mechanically connected to the Compressor Turbine and Compressor.