Since we don't know the content of the Senate resolution that established the committee, we can't say for sure what its jurisdiction was. But it is obvious that the hearing was an adversary one. Given that Pentangeli's verbal testimony contradicted his written deposition (as the Committee chair pointed out), we know for sure that he was deposed previous to the hearing, that therein he accused Michael of crimes, and therefore, Michael was a target of the committee's investigation. I think disclosure would have applied.
To clarify, are you saying that Michael should have been advised of Frankie's affidavit before Michael testified, or after? Even if this were an actual adversarial proceeding, Frankie's value only arises as a rebuttal witness to what Michael might say. The government wouldn't have to disclose his availability to possibly testify if Michael should happen to perjure himself on some undetermined subject.
