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.
I am not sure either it's a regulatory issue or just simple design flaw in their system but yes the sports betting option is not visible without logging in but there's a hint for anyone who does research can see a separate terms and conditions for sports betting that ensure its availability of the feature.