Have you actually fought him in ranked battle, or just seen him being Lght? If only seen, that's the fault of ranked battle updating only after challenges. He could have been challenged as lght main, when still being in group, then leave the group and change mains. The data stays old unless someone fights him there

Maybe this is a different player then? I mean, having similiar looking nickname, but with one letter being in other language, or sth like that...