Michigan's angler and hunter harassment law is great. Conservation officers come running almost as fast as when they receive an "officer down" call.
On lakes here, property owners actually own the ground under the water extending out so far into a lake. They are the only ones who can put in fish cover. They cannot however discourage you from fishing above it.
Depends on my mood that day as to how I would have reacted. Treat me as I would treat others and I might understand your perspective. Yell scream and be offensive and I found a trigger that I might exploit from time to time for my own amusement. Might even take my daughter there to teach an important leason at the owners expense