And? If there's no middle man then ultimately someone (in this case it sounds like the buyer) has total control over the transaction. It doesn't matter what UPS says, if they don't want to release the funds they don't have to.
In a dark market like this the ONLY protection you have against fraud is the other party's reputation.
Did you even read the article? It describes how a third party (arbiter) is agreed to by each party. It takes 2 out of 3 signatures to finalize the transaction (minus arbiter fee).