The shopkeeper was too weak. Why bother interacting so long with the freak. Just yell"get out of my shop" fiercely. Don't say "sir" and "I am Canadian". Why bother? I shouted to rude customers " get out of my shop", a group of five and they did. If you try to be polite, they will take a stronger stance. Look at what the California restaurant worker did. Just yell "get out now" then they will listen.