Maybe that's a regulatory issue. I can't really put every piece together and make some sense out of it but I can't think of any other reason. Tbh I don't know if any other casino that does that. (hiding sports betting unless you create an account)
I do not think it is a regulatory issue. Metawin restrict users from many countries just like other regulated gambling sites. See their lists below:
1.3.0. Afghanistan, Algeria, Angola, Belarus, Burma, Central African Republic, Cuba,
Democratic Republic of the Congo, Eritrea, Haiti, Holy See, Iran, Iraq, Kyrgystan, Lebanon,
Libya, North Korea, Palestine State, Republic of Ireland, Rwanda, Sierra Leone, Somalia,
South Sudan, Sudan, Syria, Venezuela, Yemen, Zimbabwe and the American states of
Nevada (USA), Washington (USA), Georgia (USA), Minnesota (USA), Mississippi (USA),
Montana (USA), South Dakota (USA) and any other countries, territories or jurisdictions in
which it would be illegal to play Games or redeem Prizes.