There is already a rule about parlay, and I think it's enough really.
5. For the purpose of this competition the max odds is capped @50. Every bet above that odd, will reflect changes in the leaderboard as it was won @50.
I know he won the competition with that parlay alone, but it's so hard to win at those odds, that I think that if a player can do it they deserve the win.
You could argue that is luck and not skill that is winning the competition this way, but I don't agree with that. This competition has a decent number of players, so if it was luck winning it, you would see random players with crazy parlays winning it, but right now, I saw amine14madrid winning at least 4 of those parlays, and that granted him a win in two competitions, and he didn't won a third one, because on the last one he won a prlay like that, he ended up losing a lot of bets after it, and didn't manage to stay in top7.
So you can't really say it's luck, when on the last competitions on a pool of 150 players or more, you keep seeing the same player winning big parlays, and ending on Top7.
For me there is no need to change the rules about parlays. But that's just my opinion.