Rule #5 & "Shitposting"

>>659526 (deleted) was deleted for a Rule #5 violation, but (according to derpiboo.ru/rules) it didn’t violate any part of that rule. It didn’t contain anything defamatory, or any depictions (real or illustrated) of underage individuals, or anything targeted at an individual or group. If the rule number in the deletion log was in error, please direct me to the correct one, but I don’t see how a headcanon image, even a crass headcanon, violates any of this site’s rules.

@Background Pony #4563  
Who was involved in the headcanon?

Rule 5 also includes “Material that is intended to troll groups or individuals, and is of little or no artistic merit”. Which that image (comic sans MS text explaining how people pissed on Fluttershy and stuck gum in her hair, with fluttershy pasted in below) would certainly fall under.
 
Edit: To assist people who think that shitposting is acceptable, I’ve moved that part of rule 5 to the top. I realise making it past the first couple of sentences might be a lot of work.

@Clover the Clever  
How is that “intended to troll groups or individuals”?
 
Also, if “shitposting” isn’t allowed, it should be added to the rule, with an actual definition of what qualifies.