There must be something I don't understand about the coach v. scout relationship, because it seems really weird to me that scouts are involved in the discussions at all once the player is on the roster. You'd think from there it's basically a coaching decision, and all the scouts ought to be doing is grading the players at each position for pro scouting purposes in case there's an opportunity to upgrade further. It seems odd that they'd have any say whatsoever on the personnel configuration that the coaches want for any given week.
With the Cowboys I don't think the scouts are involved in setting the 46 man game-day roster but can override coaches on some 53 man roster decisions.
Toomer was active last week due to injuries. Carter and Cam Lawrence were both out which caused them to need another LB on the 46.
When Broaddus says that sometimes scout lose, he's referring to the 53, not the 46. Now obviously there can be some cross-over with the 46 and 53 issues due to injuries. With DE Jack Crawford injured, they must have decided that they would need DE Edwards for the 46 despite the fact that he only played 4 snaps last week.
Good GMs often override coaches on personnel decisions to some extent. Coaches tend to be short term thinkers and don't always give a lot of consideration to the future. Obviously, Toomer was a guy that the scouts thought could develop in the future but the coaches wanted the extra DE (Edwards) for this weeks game.