I LITERALLY SAID that he might not be a complete airhead but is not smart, either.
Plus all of the examples I gave is why your claim he has not made a dumb decision yet is DEBATABLE.
If you only accept "Yes" and "No" for answers, you might be surprised when you encounter the real world.
I hope to one day match your worldly experience, oh wise one.
I accept other answers besides "Yes he is dumb" and "no, he is not dumb". I also accept "If he is dumb or not is yet to be determined".
My original statement was: " He hasn't done any genius moves, but neither any dumb ones."
You have not provided a single example of him making a dumb move. The only one with potential to be a dumb move is helping Mei, but it seems unlikely. Even if it ends up biting him in the ass later, making a bad move is not the same as making a dumb one, it all depends on the information available at the time to the MC.
If anything, from what we gather from his chat with the teacher, he is a very smart, excelling at all his classes (minus the one affected by his emotional turmoil due to being dumped). But i know that is not what we are after. We don't want to be told that he is smart, we want to see that reflected in his decisions. AND SO FAR WE HAVE NOT SEEN ANY RELEVANT ONE.
So it can really be anything, and that is why i don't see why people are jumping the gun about him being an airhead. He might be, he might not. But you seem to think his options now are between being a complete airhead or a partial one, but that there is no way he can be smart.
As you say, if him not making a dumb decision yet is debatable, i am not sure why you are already assuming he is most likely dumb, but at the very least not smart.