In the line judge's defense, she was just doing her job. However, the line judge should have used discretion on such a critical juncture in the game instead of following the rules in a black and white nature- like how NBA referees tend to let more contact at the last waning seconds of a close game.
On the other hand, the line judge's responsibility seems pretty clear cut, "black and white". Did the player step over the line? Yes or No?
But ultimately, I think you're right. The prudent choice would have been to let the violation slide, because the players were at a momentous stage of the game and also (from replays) it didn't appear that the foot fault was egregious. In fact- because of the lack of different camera angles- the various replays showed on the broadcast were inconclusive in regard to whether it was an actual foot fault.
