As far as the feathers not being feathers (per that AiG claim), that's pretty debatable.
A clue to what's going on: this is probably the second Sinornithosaurus ever found. Much or all of the literature AiG and some others quote refers to the first fossil, a less clear and pretty (but fully adult) specimen shown below. There's more room for claiming the feathers might be something else on the first one.
Above, the first one.
Above, the probable second one (if it isn't a related new species).
Feather detail, first find.
Feather detail, second find.
So thanks again for posting it and saving me some work ;)