They are only illegal in the US if they allow US citizens to participate, and the majority ban US citizens. So I think you have it backward.
Then the company can fairly legitimately say "The customer lied to us about their citizenship. We took all reasonable measures to determine their citizenship, because there isn't a freely available database of which people have which citizenships"
Are you sure your country doesn't?
https://www.cryptocoinsnews.com/filecoin-ico-raises-record-2...
The SEC commissioner said that no ICO has registered as a security so far. Given that Filecoin was one of the only ICOs to openly advertise themselves as being a security, it seems like they could be in even more legal trouble than everyone else.