I think you misunderstand movement. A transport doesn’t get a combat move, then a noncombat move. It gets either or. Once a transport has unloaded its units, that’s IT for the round. No more movement.
Lightning assaults allow you to break that rule slightly, but they don’t allow you to make a second full combat move. They allow your transport to unload in two locations while still under the normal constraints of their combat movement.
For example, a Japanese lightning-transport (JLT) with 2 units aboard could sail to the seazone between Japan and the mainland, then unload 1 unit into Japan and 1 onto the mainland. Normal transports cannot do this.
OR, a JLT could sail one space south from Japan, drop a unit into Kwangtung, then, still during the same Combat Move, sail aother space further south and drop a unit into French Indo-China. Again, a normal transport couldn’t do this.
~Josh