The Federation busted up the Tantalus colony after they found out what was really going on.
Umm, nope.
Tantalus continued operating under van Gelder. And it was van Gelder's personal decision to scrap the neural neutralizer in that institution - but the same machine had previously been fully approved by the expert Dr. Noel. Heck, it apparently remained in use at Elba II as seen in "Whom Gods Destroy"...
There's no indication that Adams was insane. Ambitious, perhaps. Bitter, perhaps. Greedy, perhaps. But that's not insanity (except by Adams' own 23rd century criteria, of course!).
It really won't do to, say, witness a woman hit his husband with an axe and immediately claim "She must be stark raving mad to do that!". There would probably be a wholly logical reason for her actions, one having nothing to do with mental illness. And there certainly is logic to everything Adams does - the very same sort of logic he would be applying in his everyday work.
Timo Saloniemi