Having trouble reporting unlicensed airbnb [Canada]

I recently stayed at an airbnb with my family. As we were leaving, a bylaw officer came by with a fine for the host for not having a business license. (I should have realized they were operating illegally when their check in message mentioned being discreet but unfortunately I didn't think about it.)

I tried to report it to airbnb but they want me to write a formal letter, including my contact information, which will then get sent to the host? That seems ridiculous to me because I sent a picture of the notice and fine to airbnb, so they should have plenty of information needed. Why does the host need my letter with contact information?

I'm reluctant to go forward with the complaint because I'm not comfortable with the host receiving a copy of the letter. I'm appalled that airbnb felt that was the appropriate course of action. Any advice is appreciated!