SETI is a simplistic blunt instrument, but it's all we've got for the time being. If in fact our world leaders are collaborating with aliens who are already here, or anything like that, this is probably happening completely independently of SETI.
What SETI is capable of is a very narrow bandwidth of discovery: it looks for unusual patterns within electromagnetic noise. Think about the radio waves emanating from Earth: as stated earlier, this has only been going on for a century or so, which is a flash in the pan on a cosmic scale. And it's likely that very soon, within the next hundred years, we won't be dumping all that radio noise out into the universe anymore. This could be for reasons such as what Pandora stated (Pandora- have you read Accellerando by Charles Stross?) or it could be for the much more prosaic reason of simply saving energy by not spilling it all out into space and instead using fiber optics or something equivalent for all of our transmission needs.
So that means, for any listening civilizations out there, about a 200 year window during which we will be audible. If you're not pointing your antennas at the right dot in space at the correct cosmic moment, you wont hear us at all. And I think it's likely that other civilizations in their adolescence, such as ours, will have a similarly short window of discoverability. So unless they are deliberately sending out signals to be heard, which may be very unlikely, then even if we are pointing our antennas straight at them, we won't hear a thing.
But IMO this does not make SETI pointless. All we ever need is one lone transmission of unambiguous nature and it would change everything. And it's possible that the powers that be would be fine with making such news public- there's a big difference between the fossil transmissions of a world thousands of light years distant, and greys hanging out in a parking orbit around Earth, pulling the strings of our government.
I personally think that the fact our species is able to muster the political will and resources to take on such a search, says something positive about us.
