Patio furniture restrictions and discrimination

[Vieta Rosenberg]

My friend have been renting at the same apartment complex for 6 years. The apartment comes with patio, and the lease states that only patio furniture is allowed there.  The clause is not enforced.  He has exercise equipment on his patio (very neatly arranged, he is a personal trainer and knows how to do this efficiently and safely).  He had the same equipment in his prior 2 apartments in the same apartment complex - one on the 1st floor patio, one on the balcony of 2nd floor).  No one ever said anything.  Other tenants keep all sort of things on their patios - clothes drying racks, exercise equipment, barbeques (specifically prohibited).  Recently - management started sending him notices to remove exercise equipment.  They threatened to fine him $75 per day (illegal in CA as I understand).  When confronted with the question why he is being singled out, my friend was told that management conducts weekly inspections and sends letters to all offenders.  However, my friend have not received any such "weekly" letters before, and he is not observing anyone else clearing up their patios from "unauthorized" items.  My friend feels discriminated against and harassed.  He does not bother anyone, tries to be mindful of the neighbors, and does not exercise on the patio during resting hours.  He has a mental condition and exercising with friends helps him battle depression and anxiety.  Is there a way to settle the matter with the landlord to obtain a formal waiver of the patio equipment clause? If not - what can the landlord do to him for the non-compliance?