You haven't actually specified you are not offering this service to those in the United States (your
intentions to not break rules are not enough), making you a Foreign Broker-Dealer. Therefore you are already breaking the law by not registering with the SEC.
http://www.sec.gov/divisions/marketreg/bdguide.htmROFL, the states law have no power outside the states, when using a foreign service it works under foreign laws, which in a lot of countries they don't even exist for online services. Even if your gob knew who and where he was, it would be legally impossible to accuse him of anything. The real question would be if something can actually happen to you by hiring his services...
I'm not saying people should trust their shares to him though, that is your call, I just find it funny to read how you think the states control the world...