He signed a lease that specified what he could have on his balcony. Nobody forced him to sign the lease. If the counterparty landlord wants the flags removed, he should remove them. That's what freedom of contract is all about; one undertakes obligations in order to receive something. The vet has a leased apartment, in exchange for which he agreed to refrain from certain acts. He's violating his promise. This has absolutely nothing to do with freedom of speech, which can only be abridged by a government, not in a private contract between two consenting parties.

I agree with StrightLineLogic.

What he might do is just let them evict him over it and tell them if they sue him for any lost rent or legal costs, he'll argue that the flags were furniture and he'll make them look like asses for suing someone over two flags. They probably would not sue. He wouldn't be out any money. He'd just have to move out of this place, which he probably would welcome.

There are many landlords who would be happy to have a marine living in their complex and flying flags, esp if it gets public attention.

Any attempt by the gov't to intervene to "protect" the marine paradoxically hurts his cause and the cause of freedom.

This is boss trying to prove something. Leave the vet and his flags alone. He is being bullied.