The argument there seems to be that he had McInnes on the podcast before Proud Boys was really a thing, so the criticism levelled at him is unfair.
Yet McInnes' shit views could be seen as early as 2003 when he said borders should be closed so people would have to assimilate into a white, English-speaking way of life. Or in 2004 when he made racist comments about Asian people. Then in 2008 when he was pushed out of Vice after attending a far-right rally and writing a piece where he said he had mostly agreed with with what he had heard there. And again in 2014 when he was asked to leave a different role after having written an essay on transphobia entitled "Transphobia is perfectly natural". All this before his first appearance on Rogan's podcast.
By the time Rogan hosted McInnes for the last time in 2017, Proud Boys had already been founded, McInnes was advocating violence and had (amongst other things) openly identified as anti-Islam, levelled racist slurs at Asian-Americans, levelled racist slurs at multiple black people and espoused the "white genocide" conspiracy theory. Less than a month later he was being praised by high-profile neo-nazis and anti-semites for successfully rebranding white nationalism.
Rogan continued to defend McInnes in 2018 (across multiple podcasts), downplaying McInnes' involvement with the Proud Boys, describing it as a joke that had gotten out of hand, taking McInnes' exit from Proud Boys (which McInnes made clear was an attempt to improve his legal position) as sincere distancing from the group, disputing the idea that McInnes was a white supremacist, outright denying that he was a racist and instead describing him as a "interesting guy who says funny shit" and a "clever provocateur". By this point Proud Boys had been recognised as a white supremacist organisation by civil rights groups, the FBI had categorised various of their members as extremist threats with ties to white nationalism, they had been involved in multiple incidents of violence and were banned from the likes of Facebook, Twitter & Paypal. Meanwhile McInnes was denying that white supremacists even existed, describing the rise of neo-fascists as a hoax and claiming that black people were committing ethnic cleansing against white people in South Africa.
Even in 2020, long after everyone knew what Proud Boys was and after McInnes' awful rhetoric was clear for everyone to see, when any sensible person would be denouncing McInnes and his work, Rogan was still defending both the decision to have McInnes on the podcast and McInnes himself. "Mostly fun" isn't a description anyone with even half a brain should be applying to a man they know literally founded an extremist neo-fascist organisation.
There are a few morals to this story but prime among them is that if you happily provide a platform to an awful person with awful views then you will rightly be criticised if that awful person sets up a hate-group with the same awful views. At that point shrugging your shoulders and putting forward "he's mostly okay though" and "how was I supposed to know?" arguments doesn't cut it.