It's really hard to tell the difference between what is genuinely offensive and what is not. No easy answers. In this case, maybe there is a relatively simple rule: Supporting democracy must not in itself be regarded as offensive...
You can't have both "Free Speech" and "You Can't Say Anything Offensive" at the same time, because there is too much overlap. So you have to choose. The US constitution is pretty clear that "Free Speech" is the higher principle.