I could be wrong, but I don't think it was meant to. I think he was just messing with Sherlock as he did when he gave him his number. Nearly everything else we have seen about him gives the impression of being very careful and clinical (the exception being his willingness to meet Sherlock). Just as I don't believe he has any desire to kill Sherlock. He wants to be challenged in pulling off his crimes and for that he needs Sherlock, he needs a nemesis greater than the police. Just as Sherlock is not interested in taking on easy cases, Moriarty is not interested in carrying out or planning simple crimes.