I remember the Slipknot issue, even though the jamband may have been around first, I don't think they had ever filed for the trademark. It was probably just the opposite with the band from the 70s, they probably still held a trademark.
Luckily BAM registered the trademark with the US gov years ago, for the name 'The Slip' used in a musical context. (You can look it up here:
http://www.uspto.gov/) It offers some protection against names that sound too similar, particularly if it's within the same industry. Even though it's not exactly the same, it can be argued that it's close enough to dilute the trademark. Of course you can loose a trademark if you don't keep it alive and protect it, so hopefully they'll nip this one quickly.