Norton was a sparring partner and close friend of Frazier's. It might be as simple as that. It could well be that between the two of them, they already knew what the outcome of such a matchup would have been.
Yes, I'm sure they made a pact never to ever fight each other. As you say they were good friends. I read an account of one of their sparring sessions once, apparently Norton got a bit too big for his boots and Joe ended up putting him in his place or should I say on his arse.
This is true to some extent, and also they were stablemates, so it would've been a bit awkward for their management to set up/excecute, and a bit of a lose-lose situation.
Thanks for the info guys, seeing as all the big 70's HW's fought each other I wondered why this match-up had never happened
From what was said in Norton's book, they were friends, but if the money got to the right point, then they would fight.
Stylistically, it would have been a bad matchup for Ken. Joe would have been under Norton's overhand right, inside Kenny's hook, and could have blunted Norton's jab coming up from under with his own counter right. Ken's cross-armed defense might tend to leave the right side of his body exposed to Frazier's hook underneath, and Joe had the lower center of gravity. If, as has been reported, Frazier was able to hurt Ken in sparring, that would have given him an enormous psychological edge in such a pairing. Joe didn't freak out if hurt, the way Norton came apart at the seams against Foreman, Shavers and Cooney.
If Joe had hung on to the title long enough, I think eventually Norton would have met him in either 1974 or 75. Despite their being friends, the two of them would have stood to make too much money, and it wouldn't have been fair to deny Norton a rightful title shot.