1. Be less a racist. (racist is used as a noun here)
2. Be less of a racist.
3. She is less a friend to me.
4. She is less of a friend to me.
5. It was really more a comment than a question.
6. It was really more of a comment than a question.
I think they're all grammatically correct because I have often come across both expressions "less/more a noun" and "less/more of a noun".
fire1 1. Be less a racist. Seems unusual at best.
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fire11. Be less a racist.
Seems unusual at best.
fire12. Be less of a racist.
OK.
fire13. She is less a friend to me.
4. She is less of a friend to me.
In isolation these seem lacking a comparison (e.g. "... than a ~").
fire15. It was really