If a player is from a restricted region, they should not sign up even though they can bypass the restrictions by using a VPN. The reason casinos are VPN friendly because, they want to allow users to bypass possible ISP restrictions. Also, sometimes a VPN boosts your internet speed. Sometimes, VPN helps you bypass some game restrictions as well. I am not sure if this works in Spinly.
If the website does not show any warning and automatically restrict access of people who are from restricted locations, users can use this reason on their VPN use without knowing of this restriction as well as possible consequence of using VPN for bypassing restrictions.
Oppositely, if the site already warns about it, emphasizes that it is not tolerated for any violation on ToS, but the user still try to break ToS, it will not be acceptable reason.
If you are informed as not welcome, not allowed, just don't try to register your account. I can not agree more with your advice.
I checked this using a VPN with different server locations (USA, France), whether they would show any signs of warnings or not. Didn't get to see any warning dialogs. So it seems like the site doesn't warn users about being in a restricted country or blocks their site access automatically. Don't know about others, but it seemed that way to me. Users are solely responsible for their safe access to the site!
Btw, my real location isn't on their restriction list.
Anyway, a simple warning would have been better, IMO. They can easily detect users locations, so I don't think a simple popup would hurt anyone! Just my two sats...