So, here's the thing...
If you say, "Regardless of the reasonableness of your actions in the context of the fiction, if you are doing it because you are trying to gain an advantage, based on knowledge that your character wouldn't have" then you are asking...no, begging...players to lie.
The frog example in this thread is a little bit silly, but let's use it anyway: if you know that some people at your table will blow a gasket if you "metagame", that means that in order to use this strategy you have to think of something that has a strong possibility of getting you killed, without it being obvious that's what you are doing.
And maybe nobody at your table (with "your" being applicable to anybody reading this, not specifically [MENTION=6812658]Seramus[/MENTION]) would ever be such a villain, but think about what would happen at any AL or convention table.
Is that really what we want to encourage? Keeping our thoughts either locked away, or intentionally deceiving others at the table, so that we won't be prohibited from taking actions we want to take?
A similar thing came up in a thread about social skills being used on players, whether by other players or NPCs. Here's an imaginary conversation I posted:
Surely that's not what we want to encourage, but that's what happens when you start worrying about what's going on inside the head of either a player or his/her character.