I wouldn't say that at all.
A true champ often doesn't know how precisely all his natural gifts fit together while others spent years finetuning every piece of the puzzle to barely touch the vicinity of the talented some day.
I've even found that champions sometimes give ridiculous advice that's flat out wrong.
Add to all this that fighting attracts mainly bad dudes with shady backgrounds, not sensitive thinkers and you got the dilemma of learning the arts of combat.
And to further disprove that quote, GSP, a true thinking champ, is probably a great coach. I haven't seen a single episode of the new tuf, so I might be wrong but read some forum-posts.
A talent like Rampage on the other hand -physically and mentally gifted for fighting- was utterly laughable as a teach (that season I've seen a few times).