Well I think the only media that flies with them on team planes are usually just the TV and radio commentary crews. Maybe the camera crews and a couple behind the scenes TV personnel as well. It's not like they're flying around with random hockey journalists.
I don't think Lou kept them off the plane so much because of stories leaking, I would guess that he just wanted as few ''Outsiders'' as possible on the plane. Not that Chico and Doc, Steve, Dano, Deb, Maven, Loughlin, Sherry, etc, are outsiders. I think he just didn't want a large presence being with the team 24/7. I think he wanted things a little more exclusive.