I think this answer will fall under the definitive differences between non-combat and combat moves.
I can’t call any old move a combat move, unless it results in some kind of combat right? that can be taking a convoy, attacking a territory (Even if empty), or actually rolling dice.
If I move armor from Berlin to Poland, and the territories are mine, it is NCM
If I move armor from Berlin to France, and attack, it is combat.
If I load a transport and attack with the units on board that is combat.
If I load a transport for the sake of having it loaded with that unit or units… that is a NCM.
All combat moves have to be declared on the map, before dice rolling can begin, the act of moving a unit, not in combat, is a non combat move, and thus CANNOT be done on the combat turn, hence you cannot choose to fully load a transport, launch an amphibious attack, and then choose to unload only half of the said transport.
The rule should read, that a transport cannot do both a combat, and non combat move. Because it is a noncombat move to load a ground unit onto a transport, to not have it unload somewhere, even if declared, with the exception that a naval battle fails and the transport is forced to retreat.