Or are there some advantages that Legend tier players have over TL and above that I'm not seeing? That is possible.
It's about who you play not from what tees or on what green speed (if you note the name of his CC it may be he'd like faster greens, probably to practice on them for major tournaments).
A more direct answer to your question, in the Aug and Sept Legend tier opens and Jdrf thing he won 8,000c, 7,000c and 1,620c respectively all playing against only Legends. If he tiered up there would be similar competitions (or the same one with the jdrf) but, the theory is, he'd have more difficult opposition.
This bit isn't necessarily about him or a particular person. What some, especially restarts, do is get to legend and only play the premium tiered credit tournaments, they'd do it in the earlier tiers too but you don't get so many rounds there and the prizes take quite a jump at Legend. Things like the Monthly where the winner gets 8,000c. Typically they wait until near the end of the month to play so that they can see what they need for one of the three prizes and if they aren't going to get one they quit the round so as not to use one up, with 500 rounds allowed you can do this for quite a while.
While anyone that is a restart is breaking the rules, only entering these tournaments (and not playing other rr's) isn't. That is what MK thinks he's doing and he may well be right.
I just think wgt need to fix the whole tier system as, especially with many playing mostly or only coin games, it's broken.