If he hadn't revealed the vital information they had another witness for the Corleones to identify and counter that person, Michael couldn't have figured Pentangeli was alive
He confidently lied under oath believing Pentangeli was dead and Cicci had already stated he never got a direct order and there was no other witness
He would have turned up totally in the dark and the committee would have sprung Pentangeli who would have testified as planned
As seen in the movie, he didn't take the Fifth Amendment which we'd discussed was never an option and Pentangeli didn't testify against him only because of the appearance of his brother which Michael was able to arrange because of the vital information
We'd debated Michael's hidden interests, links, undeclared ownership and control in casinos, his non-existent casino holdings, no licenses in his name in Rocco linked to Michael thread
My view is still the same nobody could find any trace, no trail whatsoever connecting Michael so any investigation will end up deader than dead as it did, failing dismally