That is a good point, and yes, if you were to download this torrent it would probably be wise to set the upload bandwidth to '0'.
As for whether or not it is useful, I can see only two parties that are potentially interested in downloading this code, the first are malware makers, I don't think they'll have any qualms about downloading it, illegally or otherwise, they're criminals already, one more notch on their belt will not make a difference.
The second are researchers that want to make sure that now that Kaspersky no longer has control over their code that there are no exploits that will be known to the 'bad' guys but not to the good guys.
If that is your game and you're a professional with a good reputation and you alert Kaspersky to any holes that you find you again will be operating in a 'gray' territory but I think the law would land on your side. Anybody else downloading this is probably doing it for all the wrong reasons.
Not that a competent security researcher would need access to the source to do his job.
