Betkurus is right about this situation. The user violated their TOS. It's users own fault deposit BTC without reading TOS.
Betkurus should pay back deposited BTC. Even the user violated TOS, they can't hold his funds.
End of story.
Not really a sole fault from the user, since there is a verification before someone can play at betkurus, I think betkurus should block the person, the moment they see that the person is from the country that violated their TOS, but To withhold all balance is indeed in the TOS if a user violated it, so they got a point, but still betkurus is responsible as well