I'm surprised this is the first I've heard of this, but if what the article says is true, I'm appalled. Mind you the article does say that they know few of the facts.
But... Let's say someone made a home made computer edited image of Snape and Potter having sex (as is said to be an image that got one of the accounts suspended). It is very tasteless, but fictional works of pedophilia are not illegal (lest the classic book Lolita would be outlawed as well). And according to the article the images were private or friends-only (they say "locked", I'm assuming they mean the post was some how private).
So, as long as minors we not exposed to the image and the image was legal I think that LJ/6Ap is off their collective rocker to suspend the accounts.
But I'm still forming an opinion on this as there seem to be few available facts.
Maybe some of my friends active in the fandom communities can fill me in.
One thing I am surprised LJ has never cracked down on... Indecent icons. Here they are chasing a couple images that supposedly were friends only or private posts, yet I see a many icons showing nudity or sexual acts and they are open for everyone to see, regardless of age.
Don't get me wrong, I enjoy the icons, but it seems incongruous that they would cast a blind eye over one thing that offers no protections for minors and regularly shows adult material, but do chase after a far less common offense.