Although I'm a fan of words, here's a pic:
I imagine the distance between the strut towers is different, but if it is greater, then the bar could easily be adapted, providing the Magnum towers are as sturdy on the lateral face.
Regardless of gap space, a custom bar could be built providing the towers are sturdy enough and there is sufficient underhood clearance.
Maybe SRT will specify/install one for the next model year, although I'd guess it was considered and the argument that the LX chassis architecture is stiff enough, compared to the cost of including the bar (and an increase beyond what customers will pay), won out. Few things are as simple or easy as they first appear.