[eli]

You can sue (or threaten to sue) someone for almost any reason. I know wouldn't want to fight $600 million company, even if the law was on my side.

[rdtsc]

At the same time a $600M company would be worried about bad publicity at least somewhat.

So there are many ways of fighting them. Maybe not a direct "let's see who can outspend who over a lawsuit" but something along the lines of "Are you sure you want your name on Twitter as bullying a fun and popular blogger?" kinda fight.

[s73ver]

Not really. Unfortunately, the "bad publicity as a way to keep companies in line" is pretty hit and miss.

[eli]

If your goal is to send a strong message not to reuse photos, then this isn't even bad publicity.