This entire article could be rewritten in about ten sentences. The only reason I can see for this debate to exist, whether it's in regards to sexism or racism, is because people are defining words differently.

Most people: Racist = thinks other races are inherently inferior, hates black people/Mexicans/whatever

Him: Racist = complicit in a society where white people have advantages due to minorities being disadvantaged

Being called the first kind of racist is rather insulting. If someone defines racism that way, this article can be summed up like this:

You hate black people. You look down on them. You marginalize them, you put them down, you think you're better than them. If you say otherwise you're a liar and/or you're just in denial of your subconscious hate.

That's very different from:

You should recognize how being white in America gives you advantages you wouldn't have otherwise and not being white means having to fight an uphill battle against society. You should do what you can to change the system, you should not be complicit in the system.