I wouldn't be calm if I was the MC...
He barely prepared for the rematch. MC is going in with one ally( no castle guardians and especially, no Leigh-Mary), an unreliable source from a traitor and an obscure hint from his childhood friend, which I don't think he spent a lot of time trying to figure it out.
The queen rocked MC's shit during their last encounter. Two blows and he was incapacitated. Lumi didn't fare much better. MC is on his last life, presumably. He can't rely on going back to the past to figure out the queen's weakness.
This dude is not ready to fight the queen at all.
Good luck MC, you'll need it...