I didn't read the attachment but I have done it several times with good success when I wanted to shorten Epic paddles.
Apply heat very, very, very judiciously with a Propane or Mapp gas torch until the collar is very warm but not hot enough so you can't touch it with your bare hand for a second or two. It will twist off fairly easily with no damage if you're careful. Clean off all parts and rebond with black 3M 5200 (if I remember correctly). White 5200 works too but doesn't look quite right. Use their fast set which still takes at least overnight to cure, maybe even 24 hours. I used white 5200 because black was available only in a large, expensive tube. When you apply 5200 use it very sparingly because it's hell to clean-up and be sure to put the paddle back together while it is curing which is another reason to use it sparingly unless you want to permanently bond the two halves of your paddle together.
Some other thermoplastic bonding agent may be better so you could get things apart if you needed to at a later date. I doubt if 5200 would respond to heat.
current skis: SES Ultra. sculling boats: Fluidesign Lwt, Wintech, Empacher.