Congress didn't look foolish - they were foolish.
Zuck wasn't sworn in, so there was no way he could be prosecuted for perjury. That's the first foolish mistake. Bringing rhetorical knives to a gun fight was the second mistake. Forgetting that Zuck - more or less - stole Facebook to begin with and not treating him like a lying thief was their third mistake.
Everything that took place is that room was theatre for the simple-minded partisans and morons. It didn't mean a damn thing.