I would definitely discuss having the vet do the procedure that you want done.... it's your chicken! I know nothing of the cardiac surgery stuff, seems like an odd operation for a chicken. It seems logical to take care of the comb issue first, instead of a more involved surgery. If no...
Could also be dirt or bacteria getting caught under that comb and holding yucky stuff in his nose, causing infection. I dunno. I have never seen this before, but personally I would bust out a scalpel and some blood stop and get to work.
Edited: to answer your earlier question, dubbing has...
Some folks have gotten it into their head it's cruel to do. Me, I don't really care either way.
If this is a medical procedure, I would say go for it!! It would bleed alot but might really improve quality of life for this chicken. Or try to have your vet do it.... was the vet talking about...