I don't find anthropomorphized animals to be sexual in nature. I find it a bit strange that it's assumed most people complaining about the blog or suggesting content warnings, on the contrary, do.
The complainer is a self-proclaimed policy wonk. I am sure he knows all the corrext policies to enforce include NSFW content policies. Heck, looking at his comment history, I get the impression that he might be a policy wonk in everything.
The article contains zero content that necessitates such a warning. Your belief that it is "sexual in nature" is a misinterpretation or incorrect assumption.
No one owes you a content warning that "this site contains cartoons and that might annoy you."