I would add a bow roller. No need to move the boat forward or backwards unless you need to do so in order to get 10-15% of the total weight on the tongue.
His advice may have been good for older motors and the gas/oil pooling in the carb bowls. Also, speaking generally, storing "up" if the water wasn't drained is a freeze risk.
Or maybe he banged his knee on an "up" motor in the dark once and fixed that with his own "rule."
