Most (all?) of what MGM does these days is co-financed, and that's certainly always been the case with Stargate. Back in the day SCI FI footed the majority of the show's production budget. So it was easy enough for MGM to go along with what TPTB and the network wanted to do.
The direct-to-DVD movies were much more complicated to finance, because they required a bigger relative investment up-front from MGM. They had to gamble that they would make back their money (and then some), which largely just wasn't the case with the television shows. When the 2008-2009 sales numbers for Ark and Continuum were softer than they'd hoped, and the industry was forecasting a downturn in profitability of physical media releases, that's why we never got Revolutions or Extinction: MGM wasn't willing to carry all the risk on its own shoulders.
I suspect that's where we are now. In the post-bankruptcy era, MGM is even more risk-adverse ... and so its business model is built upon co-financing. MGM would probably be thrilled to have the franchise revived with a new series ... but it isn't willing to take on the risk of paying for it all up front. So with a series pitch and a proposed budget in hand, they'll have to convince somebody to buy the darn thing and pay for its production.