I noticed Pence in that meeting as well. My take on it was he knew what was coming and was just enjoying the show trying not to smile.
Sort of: It’s your show Mr. President, I”m just agonna sit back and enjoy it.
That is the way I saw it. VP Pence was not there to divert attention from Pres Trump, which would have happened if the media had half a chance. It had to be a challenge not to flicker any expression one way or another. Good on Pence.