They do require KYC, I bet only 3 matches on low stakes, didn't even make a profit and they locked my account and ask for KYC. Now they don't want to let me withdraw my funds.
Is that the whole story? Because I believe their system is programmed to detect behaviors that they find suspicious to protect their business.
For example: if you deposit 1 bitcoin and bet 0.0001 3 times on low stakes(then there is reason to lock your funds).
Go to Live Support if this is still on going.
He should provide more details about his case, otherwise we cant even say it as a true story.
There is no reasons for bitsler to lock his account and ask for KYC if there is nothing suspicious with the account.
It seems that you have provided a good example, as any sites may do the same thing if there is an account do big deposit but made few small bets only then try to withdraw it.
Account did something like that will be suspected as doing money laundering in most casinos.