Johan
Ex got M3 in the divorce, waiting for EU Model Y!
Why would Elon Musk trust a ting obscure supplier for the most important component of the Tesla Model S and X?
It seems this sentence is the reason you believe this issue of Fukuta being a supplier for motor components is of such importance? Or is there some other reason you seem to think this is so important, than I'm not able to grasp?
Reading Stephen's post I'm inclined to think Fukuda isn't the only possible supplier in the whole world for steel lamination stacks suitable for use in AC induction car motors built by Tesla. I'm also very inclined to believe the fact that going forward to Model 3 even more of the motor production will be vertically integrated, as Stephen suggests.
So to answer your question as to why Elon would "trust and obscure supplier" for the "most important component" (I would argue there are many equally important components, but that's semantics) the likely answer is he wouldn't and he doesn't. But if your definition of who "makes" the motor is who supplies it's subcomponents then I suggest you go look up where Fukuta gets their materials and subcomponents, and then you could likely argue that it's not really Fukuta making the components but someone else "actually making" what Fukuta in turn supplies Tesla with.