GE told Airbus they wouldn't be a supplier for the A350 back when the program was launched when it became obvious that the A350 wasn't just targeting the 787, they were going after the 777 as well (where GE has an effective monopoly). Nothing in that regard has changed - plus as K Kraut notes GE is now a risk sharing partner on the 777X so they have even less incentive to make the A350 more appealing.
Besides, GE doesn't really have something that would be readily suitable to the A350 - the GEnx is a bit small, the GE9X is too big. So GE would need to invest a billion dollars or more to create an engine optimized for the A350. Unless GE thinks they could offer a major improvement in fuel burn/operating costs relative to the Trent (and take over the lions share of the A350 market - like they did on the 777 with the GE90-115B) it wouldn't make economic sense.
In short, I seriously doubt it'll happen - probably just someone trying muddy the water to get a better deal out of Rolls.