In the company I work for, the captain keeps his hand on the thrust leavers until V1 because in the event of an RTO, it’s him that stops the aircraft. As far as I’m aware, the captain’s hand comes away from the leavers at V1 so that there is no reflex reaction to stop the aircraft after V1 should something go bang. It removes the temptation to try and stop, when the decision has already been made to go, that’s my understanding of it anyway.
