I would think with Phil Costa's back issues flaring up after only 3 plays (actually 1 play, but he gutted it out for the next 2) on Wednesday night that the Cowboys are not going to be able to trust him next week against Seattle, and probably not for several weeks, or longer. (I'm not a doctor, but just based on the fact that the back injury has already recurred for Costa in a short window of time, it leads one to believe that it very much could recur again at any time.)
You can't go into games with an active lineman who you can't trust to last more than a few plays. It wastes a valuable roster slot on your 46-man game-day roster.
I think it is fine to start Ryan Cook going forward. The problem is, who do we activate behind him? Phil Costa? Can't do it unless you know he's going to hold up. David Arkin? I would want no part of him this year the way he got pushed over by second or third-stringers in the last pre-season game. Who?
Kevin Kowalski could be the backup solution when he's eligible to come off PUP, but that's not for several weeks.
Mackenzy Bernadeau? They were talking about getting him trained up at Center, but seemed to move away from that when he was hurt and needed all his reps at RG. They might go back to making him plan B until Kowalski's ready.
The problem with using Bernadeau, and keeping Costa and Arkin inactive is you go into games with only 7 linemen. We were forced to use all 8 actives on Wednesday.
I think the Cowboys need to make some roster moves on the O-line, and expect them to do so before the Seattle game.