There seems to be much convergent evidence that people who self-identify as "black" tend to test more poorly on some standard measures of cognitive ability than do people who self-identify as "white", and I don't think acknowledging that makes someone racist.

Yes, it does, by definition. If you disagree, define racism in a way such that someone who believes different races have different distributions of attributes is not racist.

The problem is we have two meanings of "racist". One is "a person who believes the distribution of traits differs among races". The other is, roughly, "a person who hates members of other races". Most people believe these are equivalent.