Some players don't show in the legend elo leaderboard

[CrossyChainsaw]

In the following images you can see the player shaw. His sentinel has 2618 elo,

However on his brawlmance profile it doesn't show elo for his legends

And therefore not present in the leaderboard:

I have a theory but i'm not sure about it. It only shows people in the legend elo leaderboard, if they are in one of the legend mastery leaderboards, but i'm not sure about it.