While the vast majority of Americans would never burn, spit-on, etc on the American flag, it's still freedom of speech. There have been supreme court rulings affirming this right. The U.S. government technically doesn't even own the flags these people are doing whatever to. You should be able to do anything you want to your own stuff as long as it doesn't potentially harm you or others. Trump wants these people thrown in jail and/or loss of citizenship. For the Republican Party, who has always preached against the threat of "Big Government" never seems to have a problem implementing fascism when they get power. It may be in bad taste, but it is and should remain legal. Who knows what civil liberties may be next?