I have thought about the same. I assume it depends on the torque you need to apply to loosen/tighten the bolts and nuts. I haven't looked into the details but just from guessing I would say the 5 clutch bolts don't need high torque but maybe the primary drive nut and the flywheel bolt need a torque well above what the engine would deliver to the transmission, therefore I would be hesitating to strain the transmission with that torque.
Details: Our bike delivers ~33 Nm max. torque (from factory). Acc. to Jamie's dreamgate webpage, the primary drive bolt needs 95 Nm when tightening, maybe more when loosening. That is roughly 3x the engine's torque. Make your own estimate whether the transmission is prepared to take that load.
Maybe my way of thinking is way to conservative but I tend to be quite careful in such cases. I have seen pictures of engine strip downs where rotation of the crank is prevented by blocking the conrod with a socket extension over a few wooden blocks. I wouldn't do that with my engine, the risk of deforming the conrod little end eye with such an undistributed load is IMO too high.

gepe.