The fact that mod's don't ban scamers makes them useless.
As for the proof here's a screen shot of the payment. http://postimg.org/image/pmctfn76r/ the who.is for the http://who.is/whois/http://toxcoin.com the site was created on December 30 2014, which should have been a red flag. I don't know if I want to take the time to completely find out who he is,
It is simple : the staff doesn't involve in any "scam accusation" they are not judges and this is a forum not a law court. If it seems a scam doesn't sign up, you should no trust no one.
It isn't a scam accusation when there is plenty of proof and it's not just me, and no asked them to be judges but in every other forum I use mods ban scammers. And most forums have some type of "shit" list where banned users go.
No I don't think this is the right decision to resolve the problem, I have heard they don't ban the scammer users because they (scammer) may repay all the other users. So the unique way is : give them a negative trust and stop. You can try to "ask" the scammer if he will give you back the money (in some cases it worked).