I did read it, it seems the main issue is the damn, he wouldn't be able to cross without trespassing because of the damn. But feel free to link to whatever you got that says you're trespassing on top of the water. Also link to the jail time he received.Apparently you didn't actually read the case, because that's exactly what happened to Mr. Givens. He received a substantial fine and some jail time I believe for trespassing.
Actually the issue of the navigability of the Flint River has been addressed by a federal court.
Link for this too please.