Maybe I'm missing something, but wouldn't an ideal Osprey escort be able to land on our small deck carriers that could move around with the Ospreys? If not on the same ship, at least one in the same group. Wouldn't that escort be the Harrier? Or possibly a F/A-18 from a big carrier or from land based Marines? I don't see any of these prop based airplanes being a better option than what we have now..
The issue is that while the V-22 is much faster than a helo, it still isn't as fast as a jet. Also, since jets are also thirsty beasts, they may have the range for a mission with the V-22s, but not the endurance. This throws them into detached escort.
Honestly though, if the threat is so high we desperately need attached escort, it's probably high enough that a prop plane isn't that survivable. Being that the V-22 is also a prop plane in that regime, maybe there needs to be some more SEAD done up front.