Live_Journal are asshats, pure and simple. They're in it to make money, not support political freedom. And I understand that. If anything remotely controversial shows up on their radar, they're going to shut it down, simply because they don't want to both with the potential litigation.
scans_daily's postings, for the most part, qualify as fair use. They don't put up full comics, just interesting pages for the purpose of commentary and criticism.
I don't think Peter David was the first Marvel writer to notice it. Frankly, I'd assume that plenty of people at Marvel knew about it. But he might have inadvertantly set something in motion, perhaps prompting someone at Marvel to contact Live Journal with concerns and that LJ to do a preemptive suspension.
I can be sure that Marvel's creative people did not want this. They're aware of the fact that the Internet interprets censorship as damage and routes around it and are trying to get their own online viewing service off the ground. They don't need the internet publicity backlash against them, that just might drive many towards more piratey sources. Marvel's lawyers, on the other hand, probably did. Corporate IP lawyers can be douchbags.