Modern "AI" research programs tend to develop relatively simple "training wheels" tasks with objectively measurable and reproducible performance. But you have at least the trappings of science. The same can't be said for most early AI work.

If there really isn't enough information in his papers to reproduce his result (I have not read them), then Lenat has to at least be suspected of painting an overly rosy picture of how awesome his creation was.

If the result is just "this is cool", then a public binary, web service, or source code release would be welcome.

Well winning the traveler tournament and designing circuits is a bit too much for just a person. Eurisko had to have done something, even if it had help or it's abilities were exaggerated. I think it's unlikely it didn't exist at all or was totally faked.

My guess is he exaggerated what it was capable of. It's also possible it really did work and he planned on capitalizing on it. Or maybe he was legitimately scared of it falling into the wrong hands and becoming unfriendly AI.