Well...no...
From my power my transformer secondary is 240 v center tap, so three wires to meter, there to panel. Main breaker disconnects 240v (two 120v 180° out of phase). This center tap is neutral and goes to driven earth ground. Garage has a sub-panel. By having main breaker off there's no incoming power, transformer center tap is grounded at pole, this lead also grounded at main panel and is neutral.
The generator backfeeds from garage to house, cannot backfeed through an open main breaker back to transformer.