Exactly. Has the agent returned the money to the tenants? Gee let's take a wild guess, no? So if the owner wouldn't take the money where did it go? If anything, the tenants should direct their anger at the agent who pocketed all their money for the last 3 months. The owner communicated crystal clear to the tenants that it was over by not renewing the lease, refusing their rent money, and erecting the sign.
Let's face it, if someone parked a food cart on your front lawn and you told them repeatedly to get off for 3 months and they didn't, eventually the cart might end up getting tipped over on the street one night. This is just a bigger lawn we are talking about.