That's a simplistic answer for a seemingly simple situation. However, I would argue that it's not. The NFL is involved in a massive lawsuit regarding concussions, because teams (as well as the players themselves) encouraged players to get back in the game. These aren't independent medical staffs making a call. It's the team-paid doctors saying whether they can go back on the field, not whether they should. I've heard that Doc McKenzie is a great person, but that said one shouldn't forget who's providing his paycheck. Coaching staffs are there to win, not to think much past this season and certainly not to think about players lives post-football.
As for my statement about the old thread, you're right. I thought that the Packers should shut him down for the season and let his ankle (injured 3 times) heal for the next season. I still stand by that statement.
And has Lacy's ankle been an issue whatsoever this season? No. So perhaps the medical professionals on our team knew what they were doing in not suggesting that he be shut down in Week 17 and the playoffs? Maybe they knew that there was little chance of this becoming a prolonged recurring injury?
Just because the NFL had some issues in the past with allowing players to play injured, that is not related in any way to the judgment and professionalism of our own medical staff. In fact, you could just as easily argue that in this day and age, it is those very lawsuits and potential negative publicity that will cause medical staffs to err on the side of caution.
I just don't know where you want to draw the line. Why on Matthews? Heck, Sitton has a torn ligament in his toe. He's an All-Pro lineman. Should we shut him down for the year just to be safe? Do we want to let Lang's ankle fully heal before we line him up again? Should Rodgers have sat out that last game against the Eagles just to be absolutely sure of his hamstring? Guys are going to have small nagging injuries all the time. If you're going to let them all sit until they're 100% every time, you're not going to be able to field a full team on Sunday.
Coach McCarthy said that Matthews looked good and that he's not concerned about him missing time. Our head coach, who certainly cares about his players, and certainly is well aware of the "big picture" of needing him for the playoffs, is not worried about him playing in Minnesota. Why would we assume that we know better than him?