I can guarantee you that Michigan Open Carry is already filing a lawsuit over this.
Yes, lawsuits are already being filed. They were already primed to go back when they tried this a couple months ago when people open carried into the capital during the fight against Whitmer’s illegal (and still illegal but she is doing it anyway) covid orders. So, Michigan open carry already has a lot of the work done.
i carry concealed, so, open carry doesn’t matter to me. but those that want to, your choice. i’m guessing in the future for all state and local govt. buildings they will do what the feds do. ban all weapons as usual.