

I don’t need to explain anything. If you want to host something with content that is illegal in another state and you choose to not put up any protections to block users from accessing the content in that state, you very well may be sued some day. If you block users from signing up from those states and/or block those IP addresses from accessing your site, you likely would have grounds for it to be dismissed before ever having to do anything. State lines do not protect you against lawsuits.
https://constitution.congress.gov/browse/essay/artIV-S1-5-1/ALDE_00013024/
If you are fined in one state they will ask your state to enforce the penalty and they are usually legally required to do so by the federal government.
The part of Mississippi saying it may have criminal punishments as well may have more leeway, as you won’t get extradited if it isn’t a felony in most states. But we don’t know what the criminal charges would be. At 10,000 per user signed up from their state though, I’d be weary.
Just be careful, I’m just saying it’s risky. I can see them ceasing your assets in another state because it follows the current laws. Otherwise if you found someone guilty in a state court you would just move to another state and be fine, which we know doesn’t work, or people like the my pillow guy would just move out of Minnesota where he was found guilty, to say Texas.