I think this is a case where more than one thing can be true.
Luck absolutely should look out for his long term health, especially if playing the game was no longer fun and had become too much of a burden for him.
HOWEVER, I also think it's fair to criticize the timing of it all. He plays the most important position in sports. Quarterbacks literally hold the fate of the coaching staff and success of the franchise in their hands. Knowing that you're in that position of importance/power I think you owe it to your team to make that decision more than 2 weeks out. If the injury came about in April, by mid to late July he should have made the call as to whether he's in or out.