If my local sportsbook doesn't post a money line on a football game, does that mean that they really don't want to take any bets on it?

Yes. That was because they didn't know if Stafford would be able to play until shortly before the game.

Commonly, this could mean an imbalanced book on the part of the sportsbook, or there is concern over players being able/unable to play.

There are times you'll see it listed as OFF, meaning that they aren't taking bets. The Steelers v Bengals games was taken off for example because the Steelers had put Ben on the Covid list(among other players) and it wasn't known if he would be playing that game. Well the bookies couldn't set a line without knowing who would play, it changes the game and points so much(look at last season). If they don't post a line they aren't taking bets.

Well look at the game, if your a bookie would you want to take that game on?