It is common practice for a HOA to place a lien on a property for asthetics issues if the bylaws set in the covenants are violated.  Once he stops doing business the MOA has absolutely NO legal position on Asthetics.  Zoning laws are for addressing land use for business, not personal property storage. He should stand his ground.   If he decides to tidy up his property to make neighbors happy, who is the "looks good enough" cop?  Just another opinion whoever it is..  Bottom line talk to your neighbors make friends help each other out.  A stroke is a difficult injury to overcome; and he's a Vet? 👍  Who knows he might just have that part for your refrigerator that just quit working...