You raise all your defenses in the trial, you only get one. If they'd wanted to put all their eggs on the statute of limitations point then they could, but you can understand why defense lawyers generally don't do that.

From other comments, it came down to when Musk could reasonably be judged as aware of the injury.

Agree. If this is a precondition, why force people to share their diaries and stuff? Is it all to claim they hid material things that would have led to an earlier filing?