888 and Party are publicly traded companies. They have shareholders to appease, and operating illegally is not the way to instill trust with your shareholders. There is no ulterior motive here, they are doing what they have to do to survive. They both are very large and have significant revenue coming from non-US gamblers. Why loose everything when you can maintain something that is still very lucrative.
What will be telling is if the privately held sites do the same.
The point about GW not signing this is just silly. I wish it would happen as much as anyone else, but I don’t think he will shrug off port security just because he wants a vacation. He may be stupid, but he isn’t dumb.