There are a lot of a$$hats on imgflip. Usually easily ignorable. This dude's just a troll masquerading as a moralist. If you have any problems along the lines of this guy and need help let me know.
Anime is esoteric. The vast majority of people have never even seen any. Why would anyone necessarily know plot lines? Knowledge is power when knowledge is known. Chasing around a young girl with comments trying to take the high ground is creepier than fictional incest.
Dude I haven't checked any of their other posts, the only reason I come back here is because people respond to my comments. Plus I made those comments in passing so it hardly is "chasing".