Well I still do not understand glad's meaning of "Mains" or "mains" either...
I do see the U.S. desire to forward deploy the F-35 earlier than other platforms. While it is partially political, it might also be desirable to see how the F-35 works, gain valuable training for crews and allies (and perhaps boost sales) and see how it will influence doctrine in the services. Even if the F-35 is not fully up yet, they offer some impressive capabilities.
Why not deploy them? Why wait until FOC? The system will be constantly be updated over the life of the program. Do you wait until all your dream home improvement projects are completed to perfection to have friends over? Nah, I say invite them over- most won't care if your don't have the bamboo floors in yet....
In the US, there was some flack about not deploying the F-117, B-2, F-22 and B-1 to certain engagements or hot spots.