Every time Rand Paul is the last holdout, it tells his constituency back home they are the most powerful people in the world. Rand Paul has to be chased by the President and Rand makes his concerns and wins concessions. The vote for Pompeo is yet another proof of the power of his constituency.
His "no" vote is a permanent placemark for the GOP. Libertarians never have a grand win to influence policy. Rand Paul says that is not so anytime he votes "no."
That "no" vote holds his place with his constituency, but, also glues the Libertarian Party together.