Many people underestimate the importance the Rams' place on special teams. If Jo Jo is the best option at a position that touches the ball 4 - 6 times a game, the Rams' won't cut him in favor of a six wide receiver. Jo Jo has been both sure handed and electric at times, and McVay trusts him. I suspect it will take injuries to other position groups rather than a non-dressing sixth receiver to move him off the roster.
