Can someone explain to me why this argument is invalid and what is the rule that is apparently missing?

"Percy lives with his poodle in a New York City residential building with more than ten units. Therefore, if Percy has openly and notoriously kept his poodle for three months or more, then his landlord cannot force him to get rid of it."

From what I understood the rules to be in the previous lesson, if someone who lives in NYC in a residential building with + 10 units has "openly and notoriously" kept the pet for 3+ months (which is exactly what this statement is saying), then that person cannot be forced to get rid of it.

PS. Also, how hard was it for whoever wrote this lesson to explain (in English) what the missing rule was?

All that and I still have no idea what the missing rule was.

Bro... hobbits are always short. Get your facts straight.