Almost, but nope. Rheinland doesn't really care about Omega-3, as of now. Altough it does possess a shipyard, and a habitable planet, It's not as rich as the deep Omegas. They won't care about GC too much, since Bretonia taking it means both the corsairs and the hessians get denied of a rather great deal of market, and supplies.
And while it's easy to guess that Port Jackson came to life to have a Bretonian beachhead when it wants to take the planet, and push into the omegas, it was rushed. Now the RP reason is denying the Gallics reinforcements from their Corsair allies, by taking out their best supply point towards Bretonia. And since someone will come to b**** about why are we sending forces when NL is under siege, those are the ships that are unfit against the gauls, on the note of being obsolete designs