Well its not like they can magically build gundams they simply have access to the power source they use, Generally speaking they can't even make a completely new Mech to use a Solar Furnace as they have stated that would take a decade or more. So I imagine they are just going to slap them on existing mecha. Its still complete BS unless Celestial being has something more powerful in reserve.

Heck at this point it seems that are purposefully escalating war I'm beginning to think the grand plan is to kill everyone so there will no longer be any wars. Thats about all that the actions taking place can result in anyway.