The point of the hearings is to continue to enflame the passions of Republicans and Republican-leaning independents. The mere presence of the committee does that, and "looking stupid" doesn't hurt. If anything, it helps - "that woman made our side look dumb!!"

He's not trying to win any Democratic votes. And true swing voters are down to a meaningless percentage of the electorate.

Additionally, he's feeding the media that is desperate to cover anything other than issues.

So why shut it down? It's working very well and will continue to work well.