I understand the context, but what I'm asking is; do US intelligence officers make completely truthful statements as a public as a practice? Or is their expertise rather in acquiring, analyzing and compartmentalizing information.
> do US intelligence officers make completely truthful statements as a public as a practice?
No. Intel (especially counter intel) officers are, trained to give information to convince someone of a certain context. Whether that information is true depends on the situation.
But it’s certainly not common for anyone to lie under oath, especially when they are testifying that specific people and corporations are involved in illegal operations. He’s opened himself up to not only perjury, but also lawsuits of false accusations. I don’t think the billion dollar defense contractors would have any trouble suing David Grusch if he’s lying.
I think there is a pretty good record of high-level intelligence officials lying to Congress under oath, and a similar history of no consequences whatsoever when the lie was later revealed. WMDs in Irak and the inexistence of the PRISM program were both testified about in Congress, and later turned out to be lies. Which high-level intelligence officials were ever even investigated for perjury?
Even still, you’ve completely ignored the other half of my comment. Grusch is alleging specific people and corporations are involved in illegal activities. The corporations should have no trouble suing Grusch for false accusations and defamation, which in this case would be equivalent to jail time. So even if congress didn’t refer him to the justice department for perjury, those corporations absolutely will sue Grusch if he’s lying.
It's also a very different thing to lie to Congress with the backing of the IC (as happened with Clapper, WMDs, etc.) compared to lying to Congress against the IC's wishes. You are astronomically more likely to be prosecuted for the latter.