Of course they won’t admit it, but I’ll bet there isn’t a single Republican ex-prosecutor in that hearing room who wouldn’t use Cohen as a witness to secure a conviction against a mobster. Why? Because between a rat and a godfather, most jurors will believe the rat.
In the courts, prosecutors use mafia turncoats, jailhouse snitches, and accessories to crimes (the getaway driver, the best buddy who helped bury the body and threw the gun in a lake, etc.) — i.e., bad people — as witnesses all the time. Many criminals would go scot-free if they didn’t.
And jurors have no problem believing them.