It depends on the locale, and I’m not saying I agree with it, but you might want to reconsider your view on the law. A roommate situation does not create a blanket permission to “discriminate.”
https://www.chicagotribune.com/news/ct-xpm-1997-05-22-9705230273-story.html
Advertising is different—read the link I posted.
No, SCP—this didn’t involve a situation whereby the roommate opening was advertised as “no conservative Fox types need apply”—that is completely different.
You owe AAA Best an apology.