Depends on how you define racism: is it a descriptive (this is a fact about the world that I consider to be true: this group is smart, that group is not) or perceptive (this is what I want to see in the world: this group should be given privileges, that group should not) view? In the email, his own statement is the former, and his assumed definition of racism clearly only relates to the latter.

He said that black people have lower IQ, which is true. You are the one who translated that to "black people are inferior". You are the one who is equating intelligence with superiority. You are projecting this belief onto him. Reasonable people can simultaneously believe two truths: "black people have lower IQ" and "black people are not inferior".