It looks as though the HS in Cass County is paid to do animal control work both for the county and for the city of Logansport. Logansport defines pretty much what I said earlier, that there needs to be evidence of cruelty or disturbance for them to impound the dog. "Disturbance" can be as simple as running loose but once the dog was contained and cared for I'm sure they had no authority to insist on taking it.
Any animal may be captured and impounded by any peace officer if such animal:
1) Is found running at large within the city.
2) Is a menace to persons or other animals.
3) Is suffering or reasonable suspected to be suffering from an infection or contagious
disease.
4) Causes serious annoyance or disturbance to persons in the neighborhood by habitual
howling, yelping, barking, meowing or any other type of loud noises or otherwise.
5) Is kept in any unsanitary manner thereby causing odors which are annoying and
disturbing to the persons in the neighborhood.
6) Is treated by the owner in a cruel or inhumane manner or be considered as an
abandoned animal.
I didn't find the ordinance for the county, but it's not likely he had the authority he exercised.
As a Humane Society, the shelter probably has a board that controls actions, hires employees, etc. My suggestion is that they need to know how this person is behaving and reel him in a bit. Your vet might even be involved or suggest who could be called to politely express your concern. If they are organized, that may be enough to change behavior in the future.
I do suggest that you tell someone with some authority because I've seen people in such position get increasingly abusive in taking animals until someone stops them or replaces them.
Rule 4 sucks. We have 1 neighbor we don't get along with (well, nobody gets along with him) who has threatened to call the law on us because one of our dogs barks a lot. It is not like the dog is out in the yard barking all day, or at night when people are sleeping. He's just a butt trying to get even because we told him off one day when we got sick of his mouth.