The captain obviously realized following the decision to reject takeoff, that the thrust reduction would result in a rapid de-rotation resulting in a violent impact of the nose gear on the runway.
Sorry, but that is just stupid. First off, whatever was causing the nose to already in the air at 30 knots wouldn't magically go away with a thrust reduction - the only way the nose might come down hard would be if he stood on the brakes. An RTO at less than 50 knots doesn't even NEED the brakes.
