I know what you mean, at times I don't want to know who killed Hariri as-well because I'm fully aware of the consequences. We are on the verge of exploding. It's about time.
I consider Nasrallah one of the smartest politicians as-well, no question about it. But to answer your post, there are many possibilities, and Nasrallah should know this and accept it before giving indications on where this tribunal is going.
Look, lets say one of Hezbollah men did this, Nasrallah and the big heads were not aware of this, isn't this possible? Isn't there a spy in every country, every party every organization it's possible I say but the worst part is that Nasrallah made it clear that if one of his men any man, from the smallest guard to the big ones are accused he will not hand no one and he will consider it as if they're accusing Hezbollah as an organization which is completely wrong.
Then again, they could be innocent and probably no one will accuse them but putting conditions when things are still not clear makes things fishy and suspicious at times IMO.