The procedure to stop the barrel from spinning loose seems to be over complicated (I could be wrong though).

Has anyone tried running two set screws through either side of the insulator to pinch the barrel (stopping it from being able to spin)?

You don't want to pinch the barrel or the filament may get stuck, as well as the flow rate out will also be lower.

If however you use PEEK instead of PTFE, you can try using a high temp threadlocker, eg LocTite 680 to secure it in.
Though to use a thread locker, you will have to use a plastic that resists some chemicals like PEEK and not PTFE, as its super non stickm so threadlocker would not stick to it.

hmm, yeah that makes sense. but if you drill the insulator then insert the barrel and mark it, you can remove the barrel, use a dremel to flatten the marked spot, then bolt it all together, should prevent the rig from turning?

I may give it a try, or i may just stop complaining and do it the way everyone else does