For the future let's see how they will manage external contributions. Opening the code for transparency is a good point (even if this still doesn't ensure you that the same version of the code is running in production on trusted hardware), but doing this on GitHub will certainly bring some contributions. Will they refuse everything? Or accept external contributions? Will they use GitHub as the central development process? If not how are they going to handle the development in intern in regards with external contributions? Also are they going to do all commits with this dedicated state-account? Who will be part and what would be the process for reviewing and accepting external contributions, to be sure they are not adding backdors purposely desguised as mistakes? Having a state starting to work on open-sourcing such a sensitive software in Switzerland opens a wide range of interesting questions. Maybe, and probably, this has already been discussed in other countries or even other part of Switzerland, but in the state of Valais (Switzerland) this is at least not the case.
It's not the first project under state control in Switzerland that is on GitHub. I'm also aware of geo-admin [2] who have their sources there. As far as I saw, they are handling GitHub much more professionally.
[0] https://github.com/republique-et-canton-de-geneve/chvote-1-0
[1] https://github.com/republique-et-canton-de-geneve/chvote-1-0...