I would say yes, given your facts. He could OC on his lot, he pays rent; therefore it is his property. The park as a whole is private property leased to each individual by the month. Private property rights govern the rules.
However, I don't think the courts will see this as a good reason for eviction and may deny the claim.
I would suspect, given the owner/managers quick and severe response...there may be more conflict between them than just a gun.