I'm suggesting precisely that. Maybe not a change of mind, but he could have said he was compelled to flag, but also that he will now tell Attwell that Rashford didn't touch the ball. It's only speculation, of course, but Fernandes was certainly happy after the conversation.
Cann is best buddies with Howard Webb of course. Cann and Mullarkey were linesmen to Webb for much of Webb's career. Webb described him as one of the best linesmen in the world.
Webb, the known Rag sympathiser, now being Cann's boss. And if anyone thinks Attwell carries any seniority in that relationship, I think they are deluded. Cann had almost 20 year's experience in the PL, and as you say has officiated at a World Cup final and in latter stages of the CL. Attwell hasn't the personality to be anything other than a yes man.