Playing Devil's Advocate here for a moment, I think what Cergorach's main objection is the open naming of the artist who plagurized the work in the press release. Whether or not the information is factual concerning the plagurism, in some courts of law (depending on the judge), you could be walking a fine legal line of slander. Perhaps a better way to put it would have been:
"...some of the artwork proferred by one of the primary artists for Dawning Star was derivative of and unattributed to another artist, which was passed off as his own. In short, plagarism.
First, I would like to offer my deepest apologies to Travis Charest, the artist whose work was lifted. I can assure you that I was unaware of the error..."
You could then simply add a statement saying that publishers interested in more details should contact you directly. This way, you still get the word out about the project being delayed and let publishers know that you are willing to discuss this individual
privately without creating this drawn out and confrontational discussion over the merit of naming names publicly. It adds a little more professionalism to the release and still provides relevant details that the public need only know.
Just a thought from an objective outsider...