Even Stake.com can give you a tighten verification depending on your account activity. It’s ridiculous to think that a casino will resort to this extent of verification with that amount because they can just do regular KYC and process withdrawal since the amount is too small that can heavily affect the operation.
I will understand if we are talking about hundreds of thousand or more while user is showing sign of illegal activity such as laundering but I doubt an amount like this involved on illegal activity.
More than likely, this bookmaker is just looking for some loopholes if given the chance. I never heard of such verifying the location of the player. They are not officially stated in their terms. So if you happen to play on this site and have funds, better withdraw it while they are allowing you to. Because the likelihood of screwing the players is quite high.