Harris is literally talking about genetic causes for Black crime rates. If this doesn't make you alt-right, then the term has no meaning.
As far as I am aware, Harris has never professed such views. He hosted Charles Murray on his podcast-- a questionable decision, perhaps, but definitely not a blanket endorsement of everything his guest has ever written or said. Maybe there is some other controversy I'm not aware of, but this is the only time that race comes up on Harris' Wiki page.
I distinctly remember him strongly signaling agreement with these views in multiple instances, but obviously I don't remember those since I don't think about it very much. If I'm wrong I'm wrong, but he's at the very least heavily leaning in that direction.
From what I've heard, most of the accusations of racism levied against Harris hinge upon his attacks on Islam, especially on Bill Maher's show a few years back. I always thought these were totally baseless and unsubstantiated.
As far back as a decade or so ago Harris openly supported racial profiling, including--self-admittedly--of
himself if need be (Harris being Jewish and Jews, famously, looking a lot like Arabs in many cases). On the other hand, this was in the context of his opposition to Islam, so I suppose an argument could be made that it was an unseemly combination of an anti-Muslim view and a hyper-utilitarian view, rather than a racist view per se.