I don't see any mention of letting the OP to withdraw the deposit. Where am I missed?
OP confirmed they can in the OP.
You can withdraw the deposited sum only."
And the casino representative confirmed it in their reply to the player:
You can withdraw the deposited sum only.
So they're in fact ruling this in his favor due to the following
due to you not complying with these Terms, we may cancel and/or void any of your bets and withhold any money in your account (including the deposit) (General Terms and Rules 6.6)
If according to the rules they're allowed to take his deposit but choose to return it, it should close the case and this thread.