Heck, I'd love to hang a 200-hp turbine off the back of a 300CB, just to have a turbine-powered 300CB!
Oh yeah, I guess that's the 333.
Anyway, the choice of the R22 for this project seems to be driven by the same reason R22s are used almost everywhere - it what they could afford.
Heck, forget R-anything, just consider the rotor system. The teetering rotor offers precious few advantages from an aerodynamic & safety standpoint, yet they are everywhere because they are cheap to buy and operate.
Now how cool would it be to plunk the rotor system from a 300CB on top of that turbine R22?
(BTW - I am aware of the two-blade advantages in certain work, but there are lots of Bells and Robinsons out there doing everything but those jobs.)