I'm still trying to find the opinion itself (it's not on the Court's website yet), but from what the press coverage is saying, the decision was primarily on Fifth Amendment grounds rather than first. It's also worth noting that this was a ruling on a request for preliminary injunction, which means that the judge concluded that CNN/Acosta were likely to succeed, but doesn't formally rule on the underlying merits.
It's worth noting that DoJ lawyers, who are actually accountable for lying (in a court filing, at least), did not argue that Acosta had touched the White House aide.