Probably your cased is sensitive that probably involves possibility of laundering or other violations which AML policy guide needs to satisfy. If you have nothing to hide then completing this document is not big deal especially if you have huge amount of money since this possibility of KYC is written on the ToS if you read it thoroughly.

I experienced this kind of KYC on our local casino that involves proof that I’m not a government employee or any relative from government. This is very hard to prove because I need to provide certificate of employment, bank account, and other documents that will show I earned my money without any involvement by someone in the government. I’m not sure how serious your case but I think that they just need to further verify your identity such as video KYC or proof of income.