To be even more specific, you have authors who worked directly with Campbell during that time saying that they knew that he was racist and that it was wrong.
This idea that racism was normal and not remarkable in 1960s is a pernicious fiction that is promulgated by racists and their apologists. If you feel that this is an unfair inference about you, I would recommend you spend some time with history and get caught up.
It almost seems like we are witnessing another backwards swing currently.
I think we are currently seeing an attempt to swing things backward, which is why I think it's important to speak up against that.
Frederick Douglass, 1852
http://www.historyplace.com/speeches/douglass.htm
(I don't know his works well, I just searched and read...1 of them)
To select an example from popular culture: the musical "South Pacific" (1949) contains a strong and explicit anti-racist message [1]. John Campbell reflected the racist views of a fairly large segment of the American society of his day. But there was already a large, and growing, part of society that rejected these views.
It is often unhelpful to apply modern-day standards to historical figures. But Campbell is from a time and place where racism was already recognized as an evil to be fought. He has no excuse.
[1] https://en.wikipedia.org/wiki/South_Pacific_(musical)#Race
The Voting Rights Act of 1965 prohibited racial discrimination in voting. Blacks could and did certainly vote long before then. Blacks, for example, voted immediately after the Civil War. It wasn't until the end of the Reconstruction Era and the repeal of most of the Enforcement Acts that blacks were deliberately disenfranchised by state governments run by racist whites.
Racism as a concept that needed a word was barely present in the early 60s [1], until then it was completely normal and expected by everyone. Bus desegregation wasn't until 1956. "I Have a Dream" was 63. Blacks couldn't vote until 1965. We might find it surprising now, but if he had written about an integrated community then, readers would have been shocked.
Now, for us, it serves as a valuable window into past culture. On a similar note, Roddenberry's Star Trek was 1966 - featuring aliens and--more shocking: Russians--cooperating. They received flak for that but HE was visionary.
1. https://books.google.com/ngrams/graph?content=racism&year_st...