Considering the hundreds of times that President Trump has publicly attacked CNN, I would think that AT&T would have a good case contesting this decision in Court.
Trump's public comments and tweets have already weakened his administration's legal defense of the various iterations of the barely disguised Muslim ban, its attempts to ban trans people from the military, and the court martial case against Bowe Bergdahl. The sheer number of comments Trump has made about CNN dwarf anything he said about those other things. I am sure AT&T's legal team is digging through his twitter feed finding plenty of examples of the President's vendetta against the network.
Trump's public comments and tweets have already weakened his administration's legal defense of the various iterations of the barely disguised Muslim ban, its attempts to ban trans people from the military, and the court martial case against Bowe Bergdahl. The sheer number of comments Trump has made about CNN dwarf anything he said about those other things. I am sure AT&T's legal team is digging through his twitter feed finding plenty of examples of the President's vendetta against the network.