I'd caution against reading more into that than what it says.
BattleTech got a new Line Developer because technically the post's been vacant. What they did was formally give the title to the guy who's already been doing the job anyway on a "provisional" basis. And of course Leviathans got a LD because prior to very recently it's been a dead brand. It *IS* pretty interesting that Leviathans is being promoted now, but it doesn't necessarily mean anything to Shadowrun.