Well, the GUEST is a little more hysterical about it ('worldwide repercussions'?) than I'd be, but DOES make the valid point - Don't trust any source absolutely on copyright information.
It varies wildly from nation to nation to begin with. Add to that the fact that publishing companies will gladly lay claim to lyrics long in the PD, other artists often think that they've come up with 'original' works that aren't, and other silliness, the byzantine nature of copyright law to begin with, and you've got a recipe where noone's really able to say what's certain, except that copyright is chaotic.
As to the DT - the actual Digital Tradition attempts to properly credit authors, and as it has been explained on several occasions attempts to comply with relevant copyright laws. Look up threads on the "Harry Fox" slimebal...er... "protection agency" for more info on that issue. As to the Mudcat Forum, it IS an unmoderated forum, and protected material may at times get posted. I believe that it is the policy of the forum to delete such material upon being informed legitimately that it is in violation of copyright protections.
But, I'm also just a poster here. If you REALLY want to find out for certain what Max (the site's webmaster) has set for policy, go up to the upper left hand side of this window and click on the "help" link, and then click on the link to email Max. He IS a busy man (given that this site is NOT a moneymaking business, he has to do SOMETHING to keep fed), but he (or someone else that he designates) could probably answer any legitimate concerns about copyrights and the Mudcat site.