Not for nothing, but Costello, himself obviously an attorney for decades, and presumably successful, seems exasperated at the fact that prosecutors appear to him to be trying to throttle the truth in its crib.
Like the snake Trump is fond of talking about: That’s what Grand Jury prosecutors do! Why is he surprised? That said, damned if he doesn’t sound sincere and a fair bit pissed off that, at this late date, with Cohen already having served jail time for perjury, Cohen’s testimony is being given even the slightest attention by attorneys or jurors, or being accorded, by those same people, any weight or credibility at all.