As stated above, this smells fishy.
In a well regulated jurisdiction, the broker has to ask all their probing questions when you apply for an account. Withdrawal or account closure is then just a formality.
If they didn’t ask the questions at the start, they’re not in a well regulated jurisdiction, so they don’t need to be asking them now. It does sound like they just want to hold onto the money. My guess is they delay as long as possible and then offer a re-fund if you pay a penalty: expect this to be up to 50%.
Don’t have any further correspondence with them. Contact their regulator or your lawyer now.