Because this is how it used to be done ~2.5 years ago, and it nearly led to the (what would have maybe only have been temporary, however, we will never know) ruin of the BTC economy, and would have, if some people didn't bail out thousands of BTC of default from their own pockets.
EDIT: This is the tldr version of the story.
So why wasn't legal action taken? Or maybe perhaps point me to the story? I'd like to read it.
It's a cryptocurrency, governments don't regulate them, therefore there can be no action taken.