You might be surprised. If it's developed internally, they own it and all patents. If the government pays for it, not so much. For lots of things which have no commercial market (missiles, fighter jets, etc) the government ownership issue is not a consideration. But if you come up with a revolutionary technology to change how we create energy, well, you want to own that. And that could mean "we'll take partners, we'll take collaboration, but we don't want your money"
. . . which is certainly a possible explanation as to why the Lockheed-Martin people are being so cagey with any revelation as to how they propose to accomplish their miracle.But that caginess inevitably invites a “fusion energy is ten years away? Yeah, it’s always that way” reaction.