"The idea that somehow testifying to what you think is true is destructive to the system of government we have — I think, is very nearly the reverse — the exact reverse of the truth."
That's a pretty telling statement. It's not that they were speaking the truth, it's what they thought the truth was (speculation). It's as if he's hinting to what's in his manuscript. Keep selling that book John.
https://www.foxnews.com/politics/bolton-hits-back-decries-impeachment-witness-retribution