It looks like the actual definitions will be up to the Council of State -"when the air services mainly provide the transport of connecting passengers" is the critical wording I think
Article 36 I. - Article L. 6412-3 of the Transport Code is amended as follows: 1 ° At the beginning, the words: "I. -" are added; 2 ° A II worded as follows is added: “II. - Are prohibited, on the basis of Article 20 of Regulation (EC) No 1008/2008 of the European Parliament and of the Council of 24 September 2008 cited above, the regular public air transport services of passengers concerning all air links to the 'Inside French territory, the journey is also provided on the national rail network without a connection and by several daily connections of less than two and a half hours. "A decree in Council of State specifies the conditions of application of the first paragraph of this II, in particular the characteristics of the railway links concerned, which must ensure a sufficient service, and the methods according to which it can be derogated from this prohibition when the air services mainly provide the transport of connecting passengers or can be regarded as providing low-carbon air transport. It specifies the levels of carbon dioxide emissions per passenger carried per kilometer that aircraft must reach to be considered carbon-free. "The application of this ban gives rise to an assessment after a period of three years from its entry into force. " I a (new). - Within one year of the promulgation of this law, the Government presents to Parliament a report on the possibility of extending the system mentioned in I to freight flights between Paris-Charles de Gaulle airport and metropolitan areas located less than two and a half hours by train, in order to provide rail courier services as an alternative to air and road transport. II. - This article comes into force on the last Sunday in March of the year following that of the promulgation of the law.