Google is providing a free service in a field in which there is intense competition. I don't see what basis anyone would have for filing a lawsuit for not being indexed in Google.
They could argue that Google has a monopoly on online search, and that excluding people from their search results is an illegal restraint of trade. I don't think that such a case would be a cut-and-dry victory for Google if the spammer (as in this case) has the money to fight them.
Ridiculous. I don't know how the law works but I do know that if Google was to somehow lose a case like that, their entire search engine would be worthless incredibly quickly with grey hat/black hat people going crazy.