For the time yes. But when said merchants is chummy with the ones you are waging war against you might consider doing it yourself at one point. Of course it will probably take some time before said facilities are up and running. The FM 3145 spoke about the exposed state of Devil's Rock and that the production centers for the Superheavies on Mars would be ready by the end of the 3140's. The Lague might take a bit less as they have more ressources then the Republic at the end of it's life but it might still take a lot of time
Free Worlds League turned around and get a factory up in somewhere around 6-9 months.
FedSuns should take longer, as they didn't get as comprehensive of a kickstart as FWL, but the Ares should be quite buildable. Or Some evolution of it.
Foxes sell Terran salvage because they will do anything for money.
Whoever ends up owning Devil's Rock makes some, or maybe RAF actually moved the factories? I'd have to see the wording.
I could see that being the extent of production.
- Wolves let RAF superheavy abtakha run ares, dump them in a select assault cluster or SLDF general forces.
- Hegemony IIC uses Martian production
- FWL builds their own
- FedSuns builds their own
- Anyone else wanting one buys from the Foxes (taking a portion of Mars' production?)