Personally I think it might be because since maybe .... after the trial, he hasn't come out with anything new, and due to that, the only chance to get to see something MJ on Vh1 is when he's mentioned on one of the nostalgic shows, the most recent one I think would be Black to the Future.
But trust me, once July comes around, I could totally see Vh1 (but more their sister channel Vh1 Classic) doing countless MJ related specials !~