If your standard is a Nazi flag nearby means everyone is a Nazi then if some random person came to a rally or protest that you support you would consider yourself a Nazi right?
>"An Alberta MP said he was not aware a person was flying an upside down Canadian flag with a swastika on it behind him"
Someone used a red marker to draw a swastika on a Canadian flag. Big difference. I suspect it is being shared in such a way to make unengaged readers think that it was a bona-fide Third Reich banner.