And you regard this as strong counter-evidence to the claim about being a 'gateway to the alt-right'?
First, 'libertarian' and 'right' are pretty compatible. See, for example, David Koch. At https://en.wikipedia.org/wiki/David_Koch you'll see he also "considers himself a social liberal,[20] supporting women's right to choose,[21] gay rights, same-sex marriage and stem-cell research.[2][22] He opposes the war on drugs."
He's also a global warming denialist and major funder of many conservative and Republican causes and candidates.
Second, libertarianism is one gateway for the alt-right. I'll quote from the Wikipedia entry for alt-right, at https://en.wikipedia.org/wiki/Alt-right :
> There were also links between the American libertarian movement and the alt-right, despite libertarianism's general repudiation of identity politics.[55] Many senior alt-rightists previously considered themselves libertarians,[56] and the libertarian theorist Murray Rothbard has been cited as a particular link between the two movements due to his staunch anti-egalitarianism and support for ideas about differing IQ levels among racial groups. ...
> After Spencer was fired from The American Conservative, in 2008 he became managing director of Taki Theodoracopulos's right-wing website Taki's Magazine.[73][74] The website initially contained contributions largely from paleoconservatives and libertarians, but under Spencer also gave space to white nationalists like Taylor.[75] In 2009, Spencer used the term "alternative right" in the title of an article by white nationalist Kevin DeAnna;[76][77] by 2010, Spencer had moved fully from paleoconservatism to white nationalism. ...
> It was on websites like 4chan and Reddit that the term gained wider usage, and in 2015 began to grow in popularity.[91] Although there had previously been a strong left-libertarian contingent to these online spaces, there was a gradual rightward turn in chan culture centred on 4chan's politics board, /pol/.
Of course "libertarian" does not mean "alt-right", and "not all libertarians." But the topic here was one of gateway to the alt-right.
Since there is a notable connection between libertarian views and the progression towards alt-right, pointing out that someone has libertarian views is not counter-evidence.