Even if you forget about black people entirely, the US determines your race by your skin colour. That's how the American race system works. What the person you're replying is saying is that the Canadian race system uses different criteria. He's not saying racism doesn't exist, he's saying the rules are different.

If you want an example, I can give you one. It's clear that American race categories like 'African American' or Asian American' aren't based on geography when you consider what category people from Morocco or from the Middle East fall in. If you look white, you're white. That's the American system.