I mean they (SpaceX) also at the same time were the first people doing something like this and paved the way. Tons of their engineers and now at these other companies. I think you have to count ULA though since they are the only other rocket launcher for the US government in the US. Northrup is specialized in top-secret launches and while SpaceX has jumped into this space if it really is TS it is going to be launched by Northrup.