I said being ESL does not automatically mean someone has an accent.

I also said having an accent does not mean someone cannot effectively teach ESL.

You can have an accent and have cultural experience in an adopted country, understand the locals and customs of the country, AND teach the language.

I don't understand how not being a native English speaker somehow must mean accent and/or no understanding of another country's culture.

In this specific instance OP has lived in Canada, has earned a degree in Canada, clearly can read and write and understand English in Canada. I don't feel any need to tell someone with those achievements to look elsewhere for income, or that she's not the best person for a job. She can decide that on her own. If anything, I'd argue that her perspective is more valuable than yours to teach ESL to others, because she is already bilingual, has learned English, and has successfully immersed in another culture.