Ah, looking at the network tag on wiki, the feature should be tagged as "network=FR:Vit'o Bus". (if this is incorrect, please specify what it should be tagged as.) But assuming I'm correct. Attempting to tag it as "network=FR:Vit'o Bus", iD will still prompt the user to change it. If I'm correct, then I think this is an issue with iDs tagging schema.
If this is an issue you care about, and I'm correct, then I suggest you create an issue over at the iD schema GitHub to correct it. https://github.com/openstreetmap/id-tagging-schema/issues/new/choose 