There are a lot of ICO's that restrict US citizens. The ones that do restrict US Citizens are the ones that are trying to be in compliant with SEC so that they do not get fined by them. The other ones dont think about the SEC, dont even think that SEC could reach them, or just dont care about the SEC.
This is how I read your comment:
"An extradition treaty exists: No sales to US citizens. No extradition treaty: All are welcome."
lol