It's actually a higher-up military intelligence officer (Grusch) and two pilots (forget their names but they're the fighter pilots that detected and pursued the alleged "Tic-Tac" UFO) that are undergoing a congressional hearing. Like, the entirety of Congress has convened to hear what these guys have to say.
The apparent reason why there's no hard evidence being presented, or why Grusch isn't going into more detail, is because the meeting is not secure. Hence why all the major news outlets are reporting on it.
That being said, if you're not going to be a real whistleblower, like Snowden was, knowing you're under threat of persecution or prosecution and willing to accept those consequences, why even open your mouth when you can't give Congress the information they're expecting?
That's why it stinks like bullshit to me. That's why I maintain this is another "trust me, aliens" bro.