The probability that he is telling the truth is far far smaller than 5%. I would say maybe about 5e-9.
He clearly lied about having degrees from MIT and Caltech and people who are known to have made such a major lie are surely much more likely to be lying about other things.
As for his UFO claims, it's not just that they fly in the face of all accepted theories of physics but that the way he describes them has no connection to our current understanding of physics. In other words to anyone with a real physics background they sound like absolute nonsense. This is why physicists like Stanton Friedman and Eric Davis, though themselves believers in the reality of the UFO phenomenon, were/are convinced he is lying.
He clearly lied about having degrees from MIT and Caltech and people who are known to have made such a major lie are surely much more likely to be lying about other things.
As for his UFO claims, it's not just that they fly in the face of all accepted theories of physics but that the way he describes them has no connection to our current understanding of physics. In other words to anyone with a real physics background they sound like absolute nonsense. This is why physicists like Stanton Friedman and Eric Davis, though themselves believers in the reality of the UFO phenomenon, were/are convinced he is lying.