I should clarify the "Tokyo Express" reference, then. The Tokyo Express is what Allied troops called the Japanese night convoys during the Battle of Guadalcanal. While the Allies, technically, controlled the air and seas by day, at night the Japanese ruled the seas. So to resupply their troops they'd bring in high-speed destroyer convoys to drop off supplies. Come daylight they'd be well away from the island and out of range of a counterattack.
If the Caldari FW'ers start running high-speed frigate groups into Luminaire - I know, this is a pipe dream because they're more interested in pew pew - they could drop supplies from low orbit or in atmosphere. It's a big planet. There's no way the Federation can concievably seal it all off with nothing short of hundreds of ships. And what's the Federation going to do; seal off the stargates to stop them? Good luck with that.
The Federation, in turn, is at a disadvantage. While you're correct that the Federation has a supply line to draw from, they'd be drawing on supplies destined for other theaters of operation. Such as Black Rise.