It doesn't make a lot of sense to me, either. Both of the flexures (splenic and hepatic) have quite a large 'bend' in them that is natural. Those bends are held in place by 'fixture' to other organs/structures via ligaments and connective tissue fascia.
Some people do have 'kinks' that somehow develop and can cause gas to be trapped - perhaps though the development of adhesions.......? Other have a 'longer' than normal colon in certain areas that can inadvertently twist or untwist. Most people don't find out about the redundant colon unless is causes problems with pain or defecation. These sections of colon may not be held in place properly like the rest of the colon is and a twist may unfortunately result at some point. But the 'whole' of the colon is typically held in place pretty securely, so that twists don't normally occur.
Your large intestine will move somewhat during a colonoscopy, but I really doubt the procedure could 'twist back' something along the way. And if someone could change a loop, what's to stop it from twisting back if it's that 'loosely' held?????
I, for one, would like to see a picture to have a better idea of what your doctor is talking about.
As Caryopteris said, there are procedures for visceral manipulation that address hepatic and splenic flexure issues. If you have a 'normal-length' colon that is attached too tightly at some point, you might better be served looking into those procedures.
I'd like to suggest you get a second opinion on what needs to be done.
I have not heard of this and I have transcribed thousands of reports. I have heard of physical therapy that can stretch a particular ligament that can cause a twist. I think I need this, but I have not found a specialist in my area that knows about this.
A colonoscopy would temporarily move your intestines around, but I would think in most cases they would tend to migrate back into their normal position.
It didn't happen for me because they couldn't even get the scope through the twist I have at the splenic flexure.