The Alternative Left should be for people who are mostly liberal, Left or progressive in their characters, souls, politics and voting. However, we are disenchanted with some aspects of Left, especially the Cultural Left in the US. On those issues, we feel that the Left has gone too far. So while we are more conservative than the Cultural Left, we are not all the way to the social conservatism of the US Right, which mostly appalls us. So Alt Left types would be more centrist on cultural issues, not as leftwing as the Cultural Left but at the same time repulsed by the cultural reaction of the Right.
However, on economics, most Alt Left types would feel that the Western liberal/Left has not gone far enough. The Democratic Party in the US, Labor in the UK, the Socialist Party in France, and the Social Democratic PASOK in Greece have all sold the workers out badly for the rich, the corporations and capital in general. They claim to represent the working people, but instead they are traitors to the working class.
So the Alt Left would be for people who feel that the Western Liberal-Left in governments of the West is too rightwing on economic issues but too leftwing on social issues.
We would be quite leftwing in economic issues (although we would let in anyone disenchanted with rightwing economics) but more to the center on cultural matters.
Where have you been all my life?
In terms of the "dealbreakers", the only things I really disagree with this guy on are "race realism", which I'm deeply skeptical of, his views on transgender rights (which I more fully embrace) and perhaps the overarching tone of "Mindsets not welcome" and similar whispers of dogmatism.
But for the most part, what's not to like?