The appellate level decision in the case of Olech v. Willowbrook, IL (Judge Richard Posner) turned on that issue.
Very nice, but I doubt they listed “malignant animosity” as the basis of their action.
I satisfied my curiosity by reading another article about it.
There were a lot of issues at play, but the simple answer is that they claimed he hadn’t paid the rent on his dock space (which he denied) so they utilized a law that allows the confiscation of boats as compensation for debts.