4chan very rarely commits to a raid. Very. Rarely. They usually have to be extremely popular and have a hankering for pissing off 4chan directly. Plus, this site isn't popular enough to be on the radar, sorry to say. Anonymous is a vigilante group and wouldn't be involved in this. Many programmers are individual trolls who target specific sites that are somewhat small, just for bragging rights. Probably one of those.
And to wrap up any thoughts it may be a 4chan raid, they almost always end in the flooding of the server, especially since these forums have no post-limit countdown. There's only like 3 or 4 accounts doing these ads.