Some people have suggested that what is going on is so profound that if humans knew the half of it, we would run the risk of having our very personalities destroyed/erased.
This is what happens when we learn that reality itself is not even remotely what we thought it was.
This line of thinking basically suggests that our very personalities are constructed on our perceptions of reality and do not--cannot--exist in without them (i.e., in a vacuum).
Students of the Bible will see a parallel in Luke 21:26: "Men's hearts failing them for fear, and for looking after those things which are coming on the earth: for the powers of heaven shall be shaken."
One possible explanation in the interview is that the role of the the non earth intelligence was to implant thoughts into the minds of human beings.
Nor does this have to happen very often.