There's a difference between "posting" and "actively promoting".  You actively promoted the obscure cryptocurrency exchange of a scam artist who shares your ip address.  You might just be terribly unlucky, but I'm sure you can see that it looks bad.

Either way, you're right that the authorities should be contacted.  This is the FBI's website for reporting internet crime.  I'd encourage everyone who lost currency on Moonco.in to use it.  The longer we wait the less likely we'll be to recover lost funds and catch the scammer.  Don't assume everyone else will report it.

http://www.ic3.gov/complaint/default.aspx