Good. A Microsoft victory here will severely damage prospects for other antitrust actions and have a chilling effect on government oversight of mergers, which is already pretty thin.
From what I understand of the merger it seems like it would benefit gamers as a whole. It seems initially the main reason to stop this was to block Microsoft from exclusive rights over Call of Duty, which doesn't seem what Microsoft is intending to do.
Microsoft has even agreed to bring call of duty to Sony's Playstation for 10 years, and also to bring call of duty to the Nintendo switch.
Maybe I'm missing something here, but I really don't see how this would hurt the gaming market, which is what is being argued here.