Technically he hasn't earnt his place, he's not been playing in the league at all (this is the reverse of what happened earlier on in the season), if he'd earnt his place he'd have played in the league, the fact he hasn't tells you that Emery thinks Leno is superior.
He's basically a 2nd keeper who plays cup games so that our best keeper gets a rest, it's what Leno did before he got into the team and earnt his place.