If I may . . .
Neither M2k nor ADHD violated the rule in question. While M2k did have to fight ADHD in losers finals, M2k not only traditionally loses to ADHD, but he was also playing extremely poorly (evident by losing an MLG event for the first time) while ADHD was playing rather well (evident by winning an MLG event for the first time. This greatly suggests that ADHD beat M2k by natural forces, and there is very little evidence to the contrary. It is widely public knowledge that ADHD often defeats M2k (in fact, I believe ADHD is the only player to 3-0 M2k in Brawl ever), and that M2k fairs poorly against Diddy Kong.
Now, there is of course, the issue of the rumor that M2k and ADHD decided to split the prize pot. However, I do not see any rulings or penalties listed for players deciding to split the actual winnings from the event between each other. Not only would it be fiendishly impossible for MLG to regulate what players do with their winnings after obtaining them, but deciding to split their winnings is certainly not equal to manipulating the bracket. Assuming Jason and Wyatt did indeed intend to split, I believe they would have done so regardless of placing first and third, or even second and third.
The splitting of the money would have to be done after the money is payed out, after the tournament is over. Furthermore, at the time when M2k fought ADHD, BOTH PLAYERS had already suffered losses against Grand Finalist Rich Brown. Considering that both of them were looking to enter into a set against him at a disadvantage, and previous losses, with ADHD's loss being the more immediate loss at the time of losers' finals, it is a far stretch, large assumption, and unfair conclusion to say that ADHD and M2k deliberately manipulated the bracket in any way.
In conclusion, I see no rules having been broken. No where is the decision to share the prize money won between any parties of players against the rules, and there is very little to no evidence at all that there was any bracket manipulation.