Errr....The dude owns a boom yeah? Attach boom to mast, place the whole lot on the ground and twist. This 'rotates the boom into the ground' providing you the reaction force to your turning. It's a hell of a lot easier than coming up with some random knot that puts far higher point loads on your lovely carbon mast. It's what I do when i'm the only one around and it's being a bit stubborn.
Case in point there are smarter and easier ways to un-stick your mast.
Pff. That mast wasn't stuck!
four people on each side, all twisting in vain, now THAT's stuck.
Edit: Dammit Elmo, you beat me to the punch!
When he pulls it apart and the sand falls out, How the hell do you get that much sand in the mast???
Looks workable if mast isnt stuck too badly. Easiest I found is a $3 grip cloth, 2 booms, one on each side, gives you much better grip & leverage. If not shifting, soak WD40/rubber hammer gently tapping whilst twisting.