I understand that but when they do investigation, what are they look into first?
For example, when they found a gambling portal, they may first look at Whois database to see if the owner is from US according to the owner address. Or maybe they will trace if the portal is hosted on US. Without these information how can they so sure they are targetted the right person? You can edit your domain registration details (set to non-US address) easily these day and if you hosted your site in UK (which is very lenient to online gambling especially to sportsbooks), I think you are not likely to be targetted.
There are thousands of gambling portals out there and many owners are non-US residents, do you think the FBI willing to spend they time on investigeting all these portals. Of course they can do that but it is a very time consuming process. They are most likely to target those give them direct information (Whois, Server hosted etc) first.
The reason why I said no to Australia or Canada server is because Australia also ban online gambling (although Casino Rewards is based in Australia) and Canada may follow US footstep. UK is not likely to follow US at this moment I believe because of their UK based Sportsbooks.
Just my opinion. What do you said?