According to the PR, Kratos (or more specifically FTT) does not build the engines, it (supposedly) will design them.

> The people who manufacture the engines and operate the planes are the ones who need to put in the effort and pay the costs, it is not Boom who has to care.

I mean, the manufacturer usually cares in the sense that the manufacturing and operating costs inform the purchase.

Though obviously the plane would need to exist first for operators to even evaluate it.