This has been posted about a few times on here, that same scam, he emailed me too on my helmet. Anyway, all Captain needs to do is look at the private message he sent you, or his username on sign up and get his IP and ban him permanently. Then he couldn't bother anyone else.
Before anyone goes and says "But IP's change all the time". Yea they do, but subnets don't. So if my "On the sea as this guy says he is" IP is 100.232.20.10, then I ban 100.232.*.* and it will take care of all of his activity unless he changes providers of course.
Now if he is using a well known telco or cable company, then it would affect others so, not sure, hopefully he is from Indonesia or something and you can just ban him.