I would consider myself open minded and liberal and for lack of a better term, "woke". But I was born in the 80s to parents who were born in the 60s and their parents in turn were born in the 30s and so on. So my parents were raised with some racism and a bunch of sexism. That meant I grew up with a bit less racism and declining sexism, but those things were still there.
In my teens I used "gay" as a slur.
Am I awful? Can you take one look at a forum post I made in the late 90s and judge me entirely? I'm doing my best now to fix these things so hopefully my son will grow up with none of this cultural and sociological baggage, but I'm not a bad person for acting in accordance with the times 20 years ago. Nor were my parents in the 80s. Nor was Knuth in the 60s.
Is it okay what he did? No, of course not. But let's not hang the man for something that wouldn't have raised an eyebrow at the time.