As much as I respect both Adam and Jamie from their extensive builds and experiments, they occasionally surprise me with obvious hair-brained contraptions.
As well as they both understand physics and engineering, Jamie still completely missed the fact a rotating cutting blade needs either plenty of inertial mass, or mounted resistance to cut pretty much anything beyond gel or light foam. I strongly suspect even mounting the blade rigid to the MR would only provide marginally better cutting, and that is IF he can maintain control.