"Takes only one ET to break embargo."
Hmmm... aliens *normally* don't wish to communicate with us, but occasionally break an embargo. Explains why:
* Despite their mastery of the universe, the aliens who actually do contact Earth are such lousy pilots as to crash into Roswell, etc. They prolly stole a spacecraft thinking it looked easy to fly.
* Only aliens to break embargo are socially deviant... explains why they seem so fascinated with rectal probes.
* They seem to prefer areas filled with other deviants.
Since we have been radiating narrowband EM into space for only a short time, why do you think anyone even knows we exist?