I'm just going to say his decision to come back should be considered a win/win. It helps the team to have every guy in the lineup and healthy that they can get. All the more so on the blueline. Hopefully these two games can be as useful as possible in getting Gardiner ready for the playoffs. Ideally you'd like more games, but there aren't more left. It's a tough test for him to jump back into the games against, but hopefully everything goes smoothly.
But I also think it's a win for Gardiner. Not going to throw around numbers since there's no way to know for certain. But it couldn't do anything positive for his free agency payday to have his season end on a back injury. All the more so since that next deal will mostly take place in his 30s. There is a risk to be sure if he gets hurt again. But if the gamble pays off he can erase some concerns and avoid losing more money off his next deal than he would have liked. And he gets a playoff run in. That's also a pretty big win.