Setting TOGA puts the aircraft into Go Around mode so a lot of things happen. It changes the flight guidance modes and I'm not sure but it might affect the logic of the flight control laws so perhaps it would be no longer in the flare mode, so no longer transitioning from normal to direct law for the landing.
The highest amount of thrust that would have been appropriate would have been the Climb Thrust limit (two clicks less than the TOGA detent on the thrust levers), if he felt he needed more thrust than that, a go around would have been the correct option rather than continuing with the landing.