You've missed the other, more obvious probability. He's campaigning for a second term. He needs the political establishment and media screaming at him in protest to maintain his anti establishment image, despite being at the top of the establishment.
Signing this will make the headlines, and he's already in them. Expect him to sign this or something else that'll make the headlines as soon as the existing bits about him get out of the media.
Biting the hand that feeds IT
