In fact skimming the judgement the Judge seems to have an exceptional understanding of technology and how it relates to law. IANAL, but he seems to be saying if he allows WiFi to be called a 'radio communication' then it will suddenly be legal to wiretap a lot of things that are presently illegal.
Quite specifically the judge mentions:
Section 2511(2)(g) makes it lawful to intentionally intercept any radio communication that “that relates to ships, aircraft, vehicles, or person in distress,” without reference to whether such radio communication was readily accessible to the general public and not scrambled or encrypted. Should the Court interpret radio communication so broadly within the Act to include such technologies as wireless internet and cellular phones, this exception could lead to absurd results. Specifically, pursuant to this interpretation, an unauthorized intentional monitoring of a cellular phone call could be lawful should the content of the communication relate to vehicles or persons in distress, but unlawful otherwise. Further, Section 2511(2)(g) makes it lawful to intentionally intercept any radio communication transmitted by “any marine or aeronautical communications system,” which could lead to equally arbitrary results when applying the exception to communications technologies other than radio broadcast technologies, e.g., a Wi-Fi network aboard an airplane.
Note the any radio communication and that the act actually doesn't prohibit that interception even if it's scrambled or encrypted.
His problem is that if he allows Google to call Wifi radio communication suddenly it's legal to wiretap people's encrypted wifi traffic as long as it relates to vehicles or if it's aboard a plane or boat.
Basically, in my brief scanning, he seems to be saying 'Congress, this could open an absurdly tricky loophole if I say yes, please do something'.