It does replace the booster stage but it the 2nd stage isn't the satellite with its orbital corrections boosters to fine tune things, it's a rocket which provid

It does replace the booster stage but it the 2nd stage isn't the satellite with its orbital corrections boosters to fine tune things, it's a rocket which provides 75% of the delta-v. The booster stage replacement doesn't even (propose to) get the 2nd stage to the Karman line without fuel, much less something to orbit without fuel like the title reads. Replacing the booster stage is an interesting proposal, it's just not what the title conveys.