But it very well might be (biased against him).

Racism exists. Racism is widespread. People in populations that are targeted by racism are much more familiar with what racism is present than those of us in untargeted populations. Much racism is subtle and implicit.

If you can logically accept those statements, then I don't see how you can claim to know how likely the presence of bias might be. And worrying about something that could actually be true is not racism. Even if the reasons involve race. Assuming that the interviewers are thinking X or will do Y because they are white is racist. Worrying that they might is probably just being realistic.

Again, though, I am the one making this argument that you are declaring to be racist. The person you replied to wasn't. He was just expressing an anxiety he experiences, and wasn't even speculating on how likely that anxiety might be based on reality.