Found this to be interesting. According to my admittedly feeble knowledge of law and tradition and the principles this country was founded on, I think this veteran was within his rights and further has earned the right to signal his distress by flying his flag upside down, having offered his life to defend it.
It is, in some ways, a tough nut, in that we founded this country on the belief that people have the right to offend each other, but there it is. Living under the flag gives you the right to burn it in protest, if you're so inclined. It is exactly that basic freedom that makes us who we are as a nation and a people and not a bunch of poor schmucks living under a King, or much, much worse.
I think the Marinette County District Attorney might need to pull his head out of his ass, especially after citing that it's illegal to cause a disruption as any decent lawyer could tear his ass apart in court for trying to portray a difference of opinion as a disruption (I see no mention of people rioting in the streets over this). Whatever, it was an interesting story and not all that far from home, either.