Generalizing with "everything", "all", etc exclusive markers is exactly the kind of black/white divide you're arguing against. What happened to your nuanced reality within a single sentence? Not everything is black and white, but some situations are.
The person he's replying to argued against putting things on a spectrum. Does that not imply painting everything in black and white? Thus his response seems perfectly sensible to me.
He argued against putting things in a spectrum in many instances where that would be wrong, including the case under the question. What's your argument against that idea? LLM'ed too much lately?