Although it does not align with what transpired on Monday’s WWE RAW, the word is that Kevin Nash was indeed pulled from his Night of Champions match due to a health issue.
F4WOnline.com reports that an issue raised in Kevin Nash’s medicals was responsible for the change–which now has Triple H wrestling CM Punk. The specifics of the issue were unclear, but the F4W source says, “it was something that in another era Nash would have worked the match, but the company is now more cautious.”
In terms of being able to wrestle a singles match, Nash will likely not get clearance until the fall. He, theoretically, might still be available to participate in three-ways and tag matches, as those kinds of bouts would minimize his physical involvement.
As noted, sources have no answers regarding why WWE announced the Kevin Nash-CM Punk match–and spent most of Monday’s show building it up–if it knew he was going to have to be pulled from the card.