Ahh, I see. Yes, I'll openly admit that there is a major misunderstanding from my side. The way your team explained to OP on email suggested that their account is banned due to insider info --why else would you mention this point on email if that is not the reason or related at any degree to their account freezing-- and I take that it's far from it, then? OP's account is not suspected of insider info?

Would you elaborate more on the reason? You can't give evidences due to the backlash you received on previous case, okay, arguably understandable, but certainly a casino --or any busine entity-- should inform their user the reason of the banning so their user could defend themselves with proper evidence?

From what we can take from the email, the possible reasons are (1) misconduct, (2) insider info, (3) multi-alt abuse, or (4) a breach in TnC.

I think we can safely cross reason number (2) based on your own statement, and (3) because if OP is multiacc-ing, they'll quite reluctant to do KYC instead of offering them. So, point number (1) which would need you to to explain which misconduct is it because the term is very wide, or point (4) that's even more vague and widely open for misinterpretation.

I'd like to say OP raised a good point, they've offered to willingly perform KYC and you cut their way by freezing their account instead, for no clear reason if I may add. So certainly we can agree that they reserve a good degree of caution upon who they submit their info to. So, maybe all we need right now is for you to give a good gesture and tell us why you banned them in the first place. After all, as you said yourself, you have your reputation to maintain. So I think explaining why they're banned is not only a cheap price to pay for OP to do KYC and you to maintain your reputation, but also your duty on the first place.