Two different circumstances. Jerry Jones saw a replacement franchise quarterback in Dak Prescott in 2016. I extremely doubt he sees the same in Cooper Rush.
Under Jones, head coaches have been given much leeway by some observers about who they decide to suit up or carry clipboards. In my opinion, Jones has massive input in those decisions.
I think Jones and Jason Garrett's views aligned in 2016. Now I am curious to see what will happen when Dak Prescott is medically cleared to return, especially if Rush plays well during his absence.
My opinion is that Prescott will get his starter job back, which should happen with any starting quarterback sustaining an injury unless practice competition between returning starter and backup quarterback determines otherwise. That said, my personal assessment of Mike McCarthy will become more favorable if Rush remains the starter. That outcome will tell me he has asserted himself against Jones' wishes, which has been a rare occurrence since the mid-1990s (not counting much of Bill Parcells tenure).