Generally, I agree with what Ngaire says. So many times these situations are grossly exagerated in the press. Plus, these terrorist's activities are meant to affect tourism and I hate to see their tactics be sucessful.
However this situation is a little different since apparently there was some evidence uncovered that cruise ships docked in Casablanca were targets. I would expect Regent to take these threats seriously.

http://www.stratfor.com/products/premium/read_article.php?id=286693&selected=Analyses

Quote from article:
The Interior Ministry has said the plot involved attacks against resorts in Agadir, Marrakech and Essaouira, as well as against cruise ships docking in Casablanca -- and these indeed all have merit as potential jihadist targets. As one of Morocco's most popular tourist destinations, Marrakech is loaded with establishments that cater to foreigners. Agadir, which is included in many European package tours, is a coastal resort town known for its beach and Western-style nightlife, while Essaouira also is a popular destination for tourists from both Western and Eastern Europe. Also, more than a dozen U.S. and European cruise lines have port calls in Casablanca.