His goose was cooked so to speak when he got caught off the side of the test site observing UFOs on the specific night of a test flight with a few others and he was having marital problems which put his clearance on hold so the story goes. He saw the KLAS interview and putting it into the open as his way out.
IF any of his stuff is true sometimes "coming out" is a safer option, at least in our society, and just deal with the character assassination, claims about your sanity, or hope once the stuff is made public you "aren't worth killing." Or, on the good side, the public believes you and you can possible even win a whistleblower award (like in a tax fraud or government corruption situation.) And, in an odd logic, it can be claimed by "them" : "look this guy is crazy/unstable or profiteering liar, if what he is saying is true why haven't we killed or arrested him? See he is a liar or a crazy guy?" I don't this strategy of whistle-blowing works as well in some countries where they will kill whomever they want....even years later.