Hoist by their own petard
Google says it honours crawler controls such as robots.txt. If Perfect 10 was serious about preventing their images appearing on Google they should have taken the obvious step of putting crawler control files on their website.
It appears that they didn't do that. If they had they'd have sued Google for telling porkies about robot exclusion and won the case.
Of course, installing controls would have also hidden their site from surfers cruising Google for pr0n. This explains why they probably didn't install them.
To me this case sounds like pure greed by Perfect 10. They were trying to have their cake and eat it too.