Agree with all of the above. And your reading of his motivation for outing LA is, IMO, spot on.
I lost any sympathy for Landis when he tried to blackmail Lemond with threats of revealing the latter's childhood sexual abuse. (And, by the way, don't be surprised if you see blackmail -- aka extortion -- among the crimes he is charged with, if he is charged.)
I think as far as his limited confession goes, it was pretty much a case of his saying to himself, "If I have to throw myself under the bus in order to throw LA under there, I'll do it, I don't care. Big Tex is going to jail." But he did hold back just enough, he hoped, to keep himself from becoming LA's cellmate.
If you step back and look at it, though, you see there is more at issue here than Landis and his rashness and his efforts to be a tough guy. Landis was a small fry, just one more rider among many corrupted and taken advantage of by what was essentially a criminal conspiracy. This desperate, flawed athlete, filled with thoughts of revenge, strapped a bomb onto his body and walked into the big bosses' office, with the intention of taking them all out. The bosses used their long reach to buy off the bomb maker, however, and the only person who ended up getting hurt was Landis. Now, the police, also on the bosses' payroll, threaten to roll up and take our injured, raving anti-hero away. After they do, the bosses will share a laugh and a drink and life will go on as before.
I don't know about you, but I don't want to have any part in that process. None of it encourages truth or transparency -- quite the opposite, in fact -- and in any case it just isn't right. If the boss isn't going to take a fall, I say leave the foot soldier alone.