If they felt a tilt rotor was a better technical approach they definitely have the expertise to design and build one.
That is a bit of a stretch. Concept development is one thing, but expertise in helicopter design does translate especially well to the world of tiltrotors, especially in the arena of rotor dynamics.
But I think your suggestion of the political implications of a single mast un-winged craft is more to the point.
And regarding scaling:
"There is a question on the scalability on the X-2 technology at the medium class," said Scott Starrett, Sikorsky's vice president for government business development. "When you get to the utility-medium or attack-medium class, it scales nicely." However, with size and weight increases "you starting getting up to that kind of payload and physical size and it gets to be a different challenge for the technology."
For the so-called "ultra-class," which would be a vertical lift machine the size of a C-130 tactical fixed-wing transport, Starrett said that tilt-rotor technology would be the technology of choice.
So back to the entire premise of Joint Multirole - a single design paradigm spread out among different size classes. If FVL-H is out of the box for an ABC coax, how is it the technology relevant to the fundamental pursuit of the program?