It doesn't change the fact he was still able to react to it. Whether he knows of A's speed or not, he will know he's coming and can activate Susanoo in time. The only way A blitzes him before Susanoo goes up is if he can move faster than lightning.I know, but my point if, he had time to react. He knew he needs to activate the Susanoo or he dies. And this is important.
If he has no intel about Ay's speed, he won't have time to activate the Susanoo. He won't have a reason to activate it.
Though intel is full for this thread so it doesn't matter.