So what? From your post all he did was sit there tried not to laugh and bolted like a whippet (presumably to report back) the second it was over.
So what? From the clips posted I would have no difficulty not laughing at Miller either. It's been said repeatedly in relation to Ives that not laughing isn't a crime.
He came to see it- there's plenty of criticism on here about making a judgement about the show without seeing the show. He did nothing other than be there. He didn't inconvenience you or Miller. He didn't interrupt or heckle.
As for "Bolting like a whippet" - sorry but get a grip. What was he supposed to do? Stick around and fawn over Miller?