I think there's tons of content that warrants criticism, but no content that warrants harassment.
None of that sounds like a gray area to me.
Another person may well just see it as a cost of doing business, a cost of operating in the world. There will be detractors, some of those will be malevolent snakes. We can mostly just ignore those as they very rarely represent a real and immanent threat.
If you've got nothing better to do with your time than waste it trying to antagonise a situation, you're probably wasting your life. And maybe the recipient can come to understand they can choose to be flattered by the attention - if many people are exerting effort to put you down, more power to you - you might actually be doing something important, and people hate that.