Same article was linked on Reddit; the top thread there points out that the meeting must have intentionally been scheduled to make this happen. It's common knowledge in DC that Congress is in session from Monday afternoon to Thursday morning, because Congressmen and Senators have duties in their home districts (listening to constituents bitch at them) that they have to take care of on Friday/over the weekend, and it takes them at least an afternoon's flight to get home.

Don't blame the reps for not being there, at least not too harshly. Blame the asshats who WANTED the meeting to be underattended to provoke exactly this reaction rather than actually letting their arguments speak for themselves.