Actually, he DOES get to say whatever he wants. He was not in court, but in an elevator. Your first amendment rights don't end just because you are an attorney in a courthouse elevator talking bad about jurors when you lost a case.
He should be spending more time wondering why he didn't win, but absent that, he can say whatever he wants. I guess the judge can chastize him or say whatever he wants to him, but if he was fined, that's wrong. Judges don't get to sanction speech they don't like.
It does not matter if he was in an elevator or on the dark side of the Moon, he remains an officer of the court and it is just as impermissible for him to verbally attack members of a jury as it would be for him to insult the judge. There are strict codes of propriety that this guy signed on to when he was admitted to the bar, and they are in force 27/7, not just when he's in the courtroom.