Ambient Sheep. If it was a criminal act then misdirection could have been an important part of their plan. By manipulating the response to the satellite pings, the aircraft could have flown west whilst giving the search teams the impression that it was flying north or south.
Buttmonkey1; the existence of the pings might not have been widely known amongst the aircrew community but it will have been part of a specification and I would be surprised if that specification is secret. I would accept that this would require some detailed technical knowledge but I expect that this information was in the public domain, albeit not widely known.