I'm not accusing you, but the reason they conduct this KYC may be because you're trying to cheat in the $200 Freeroll Blackjack Tournament. It's possible that you created another account to join the tournament and since OP sent you the password to enter the freeroll. Or, it's possible that they detected more than two players using the same IP address.
Well to some extent, if a casino already started that their are kyc compliance casino from the beginning then no one should be surprised if they are asked for KYC along the line, and if I were the one, I would just look away and go through with the KYC since I have nothing to hide from the casino and I haven't violated any of their terms and conditions.
I think is high time we start looking at it as if it be an attack anytime a casino asks for KYC, even though they did not ask us for it when opening the account, but it's stated in the terms and conditions of the casino that you may be asked at whatever time the casino deem it fit to ask for it.