And the question is whether this is an acceptable kind of metagaming because it doesn't result in "unfair advantage" or whether it's still unacceptable because it's still using player knowledge. In the point of view of the anti-metagamers, that is. I don't care one way or another.
Right is it only a problem when the Player uses it to benefit? Frankly, if the player is being a detriment to the party (actively leading them away from cool stuff for example), I'd consider that worse!
I prefer to avoid the mental headache and it hasn't been a problem at all since I stopped caring about metagaming - and in the years since, no player has done anything to change my mind back (they all want to have fun kicking butt and exploring the world too, we're all on the same page).