I have a very good explanation that I'm willing to back up with lengthy transcripts.
Here's the semi-short version:
If I were a wolf, killing Cosmos at night would be a bad move. Mostly because he was behaving so astonishingly erratically and playing so badly that lynching him would be an easy feat... Something I was planning on accomplishing today, in fact.
Put yourself in my shoes. Day one, Cosmos grills me for information. I tell him I have a potentially important role, but refuse to elaborate. This gets me suspicious.
If, next morning, you find that your role has been confiscated, what do you do?
Do you, A: Tell him all about your role, which he again, repeatedly and unsolicitedly asks you about?
Or do you, B: Refuse to cooperate on any so-called critical plans because you don't trust him? Maybe you ask about his role in exchange for information on yours, which, you guessed it, he refuses to talk about?
What about when he asks you, with 30 minutes left in the night, for a potentially important, literally priceless item you have, which you never even told him about?
Do you give it to him even though he won't say anything about why he needs it?
What about when he says he needs to sacrifice it in a ritual??
And when he finally says that it will somehow magically mark all of the wolves, do you just roll over and say, "yeah, that's probably legit" or do you say, "I'm not participating in this incredibly shady plan?"
If I were a wolf, this would be what I'd consider the easiest lynch case of my life. I'd kill someone random then just reveal all of his clumsiness and get him deservedly killed.
He never, ever gave me any incentive at all to trust him with sensitive information, then gets incensed when I refuse to supply it.
Before today, his actions simply screamed, 'I'm a wolf!' Now, I see I was mistaken: he's not a wolf, just once again drunk on power with what's clearly an enormously powerful role.
And come on, how can you say, 'he's a usually active player who isn't saying much' when literally no one said anything of substance before today? Matt? He's barely said anything. Sane? Nope. Lucas? Nope. There was nothing important to say so I said nothing. I even told everyone before the game started that I'm working a 9 to 5 job with no internet access or reliable cell phone reception!
Like I said, transcripts later, but I have to transcribe most of it from texts, and I'm out and doing stuff at the moment. Some of the above occurred in conversation, but since Cosmos is probably human he'll back it up. He has no reason to lie.