All his business is on their territory and each of his companies is reliant on gov contracts, licenses or subsidies. Big boys, even bilionaires, are forced to sit down and negotiate.
Discussion
No, that's not big enough.
He knows that they can screw him over, if there is enough will to do so. That is even before there is a concrete threat. You think there was one? Maybe threat, or a deal.
Either way, he can tweet this at zero cost and thus impove his position, or stubornly stick to his previous revenge tweets.