A landlord wants to restrict the number of people who are able to rent his three-bedroom condo unit. Therefore, he instructs his Property Manager to advertise the property as "two bedrooms with a den". The Property Manager knows this is wrong and wants a reason why he can not comply with this request.
I think that this could be a misrepresentation of a pertinent fact, false advertising and dishonest. If the moral argument does not convince the Landlord you may recommend the following statement: "I am not an attorney, but that sounds like a good way to get sued by a fair housing advocacy group. Maybe you should consult an attorney about how much it will cost to fight that kind of lawsuit?" (Sorry, I could not resist a little Professional Services humor.