I think he turned down the invite. Not 100% on this but that's what i heard.
I think you may be confusing Bergman declining the invite to the World Pool Masters, or Shane’s decision (and Fedor, Shaw, Sky) not playing in the Predator Championship League because of the requirement to wear a Predator patch.
Shane said on Facebook he didn’t get an invitation to the World Cup. Some speculation that this is because of the refusal to play the earlier event, but I don’t buy that - Shaw, Sky and Fedor are all playing.
My own guess is that (a) Matchroom invites one “lead” player and they get to pick their partner- which is why Gorst and Filler have partners we’ve never heard of; and (b) Matchroom selected Sky as the two time Mosconi Cup MVP and then Sky chose his friend Billy because they’ve played a lot of doubles together and play well together.