He does explain why Ederson’s reaction to what Rashford may be about to do, is irrelevant by law.
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The real case for discussion is about Ederson, and whether his actions would have changed had Rashford not been there. Perhaps, but Rashford doesn't impact the goalkeeper's ability to come and play the ball. He may affect his choice to do so, and how he might shape for a save, but the law doesn't discuss how a player might behave differently if the offside player isn't present; it only discusses the ability of an opponent to play the ball.
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And no, I don’t agree with the decision. And neither does he. But he understands the laws of the game as well as anybody.