One reason such skepticism might be well founded is that the FIM has a rule against CF body work on the grounds that the sharp edges of broken parts are more dangerous than plastic or bent metal.
i highly doubt the carbon fiber subframe.
That CF could be made strong enough is not in question, however. The springs in several GM cars are now made from CF, and have been for 25 years. The 85 pound stacked steel rear leaf of the 1981 Corvette was replaced in 1982 by a CF single leaf weighing about 5 pounds. I've seen 'Vettes dragged into the body shop that had the rear suspension ripped away in a crash and the only thing left where the wheel used to be was the undamaged rear spring sticking out.