Every deal that includes a foreign investor has to pass CIFUS and then the Pres. Without their approval there is no deal on US soil.
US Treasury-Committee on Foreign Investments in the United States (CFIUS)
Sorry, but that cite doesn't apply. This isn't a foreign company investing in the US, or a foreign co. taking over a US one. This is a case where a British Co. is being sold to one based in Dubai. The Brits don't have a problem, nor do any of the other P&O customers (Australia, Canada, Germany, etc)
The best the US can do is get out of the contracts they had with P&O. Then what?