It's not clear to me if this is true or not. Two quotes from this article
https://www.reuters.com/article/hea...main-effective-until-nov-1-cnbc-idUSL4N2LM491
"Earlier on Wednesday, the Cruise Lines International Association had urged the CDC to allow for a return to sailing from U.S. ports by early July, arguing that the health agency's stance did not reflect the accelerated roll out of vaccines or cruise operators' safety advancements."
"The CDC in October issued a “conditional sailing order” that comprised a framework for a phased resumption of cruises, requiring testing and additional safeguards for crew members, as well as simulated voyages to test cruise ship operators’ ability to mitigate the risk of virus transmission."
The first quote makes it seems like they are not allowed to run cruises, but the second makes is sound like they can as along as they follow the guidlines.