Why do you think Bolton would testify truthfully? He despises Trump.
I don’t think he would chance outright perjury. I also think he is well aware of the NSA capabilities to most likely corroborate or nail him for his perjury. I think the best he has is similar crap we’ve heard from the house diplomat’s testimony of not following their rules. Bolton has the same inflated ego the others exhibited, “that clod has no right to overrule me, just look at my Ivy League degrees”.