It's an opinion about the definition about port arms and a statement about rules some ranges have.
From best practices:
Default/normal start position: Facing downrange, carbine held in both hands, stock on
belt or shouldered, muzzle downrange. Fingers will be out of the trigger guard, and the
safety must be applied if the carbine is loaded. This equates to either “port arms” or
NO uprange starts while holding the carbine!
Muzzle downrange means generally downrange, and does not have to be directly
horizontal, pointing at the backstop, unless the WSB specifies it as such
At ranges where muzzle direction is specified by the range(not the USPSA club) then
that restriction must be followed
Ultimately, the start position should be up to the stage designer, but must be clearly
stated and able to be safely assumed by the competitor.