There is already a good rail link to Cherbourg from Paris in less than 3 hours and a good ferry link directly from Cherbourg to Dublin Port in 17 hours and alternatively to Rosslare. Brest is 600 KM and at least 6 hours by rail from Paris and there is currently no ferry services to Brest from ireland and no current incentive in place to start such a service. Many years ago Irish Continental Line wanted to start a service from Rosslare to Brest but it was met by local opposition who wanted to protect Brittany Ferries jobs in Roscoff and St Malo. It would have been a better launchpad for travel to Spain than Cherbourg or Roscoff.
Its sounds like a academic paper with a bureacratic or political agenta possibly to improve the rail service to Brest. Britanny always did its own thing and had a greater affinity to the celtic countries than to the mothership in Paris.
For instance there are no toll roads in Brittany, due to the kings highway regulations.