More than just white nationalists (I would say more often white supremacists, although I don't suppose there's much of a difference), antisemitism plays a huge role in what makes an alt-righter actually alt-right. There's the the belief in a distinctly Jewish influence that's destroying traditional values, encouraging interracial and gay marriage, etc, with a lot of carryover from the older antisemitism of Europe. "The jew is the one behind it" is more or less the mantra of the alt-right, it's number one meme. This is the most alienating factor about them from far-right conservatives ("cuckservatives"), let alone the general right or centrists who have a bone to pick with feminism. Granted, you can make an argument that now seeing itself a political force of increasing power (which may just be perceptual), the alt-right may have soften its narrow focus on a Jewish conspiracy (e.g., this influence was Jewish in origin and popular with the Jewish, but it's not tied to their race) in order to be more openly acceptable either by older Trump voters or younger meme kids who want to fight the SJWs. There are jewish alt-righters, so I guess Ethan is not automatically disqualified.
The whole inflated use of alt-right really comes down to people wanting neat and easy targets to attack, where you take the worst of the worst and apply it to a larger base (i.e., everyone who disagrees with you). This is an extremely common tactic that is not unique to any side or conflict. With humor, people really struggle with conservative-leaning jokes or mockeries of otherwise acceptable targets because on one hand they may find it funny in a vacuum, but they can't dismiss the thought this is hurting them in some way by empowering their enemies. So if there's this fear that this joke appeals to the alt-right, then it becomes alt-right humor. "Guys, please don't pander to the alt-righters!" Whether it's actually funny is besides the point, since it's a sobering thought that makes laughing uncomfortable.
