I am one with your observations. GMU's economics department is an interesting creature indeed. When my professor, a GMU economics PhD by the name of Howard Baetjer, first seriously suggested I apply to a Charles Koch Institute internship, I was confused. I had never heard a real life person speak with anything but contempt for the Kochs, let alone their nonprofit or advocacy groups. I had listened to an interview with Stephen Dubner and Charles Koch on Freakonomics and knew that some people sincerely conceive of Charles Koch as merely a billionaire uber-libertarian with small government fantasies intent on unleashing the productive capacity of the everyman, that Jane Mayer's criticisms were off-base, etc. That said, whatever the Kochs' do believe is of vast importance. Their political network is mind bogglingly well-funded. After spending $250 million in the 2016 election cycle--though neither for Trump or Hillary--they stated their intention to spend as much as $400 million in 2018. From Politico:
Koch and his brother David Koch have quietly assembled, piece by piece, a privatized political and policy advocacy operation like no other in American history that today includes hundreds of donors and employs 1,200 full-time, year-round staffers in 107 offices nationwide. That’s about 3½ times as many employees as the Republican National Committee and its congressional campaign arms had on their main payrolls [in November 2015].
The honorarium that my professor would pay Bryan Caplan to come speak at my college? Paid from a donation made by the Koch Foundation.
That said, I have an enormous respect for Cowen, Hanson, and Caplan. I've seen Cowen give one of his "Conversations" in DC. I'm genuinely geeked to see Caplan next semester if he agrees to come. I'm pretty well convinced of some of the broad libertarian arguments--the negative effects of things like operational licensing, the supply and demand distortions in the Affordable Care Act, etc. I am wary of the libertarian movement, though, since their arguments are so easily co-opted by don't-give-a-fuck greedy, crony corporatists. So, like you, I observe from afar not without some interest.