I feel like I must have been corrupted by the internet or something if the tweet in question is considered "grossly offensive". It certainly isn't nice , but 18 months supervision and 150 hours of community service? I don't even know how to put my bafflement into words here.
At first glance it may seem baffling, but if you see it from the “different culture different values” framework, you realize it’s just how people there want their society to conduct itself. It’s no different, from this perspective, to how baffling may seem cultures where burping loudly in the dinner table is not frowned upon, where people really value their personal space or not, and on and on.
The USA is protected by its Supreme Court and the fact that the Constitution is impossible to amend at this point, but if the younger cohort could vote for criminalization of unpopular speech, I suspect the proposition would actually win. Definitely so on many university campuses.