I was confused when I read this too. I believe he meant having another user of Psychic Terrain, so that you can use Lele as a traditional scarfer, without having to save it for Psychic Terrain. That way, if you go too ham with ScarfLele, but you really need terrain for, say, a MegaZam sweep, someone else will still be able to provide it.You can't use Psychic Terrain with a scarf unless you're planning on spending all your turns on the field juut spamming a useless move. You could with Life Orb but if the terrain is what you're really interested in then Terrain Extender would be better.
At least that's what I assume he meant..? The post is kind of all over the place