It would have to be more than that. If it's supposed to be backed by EU there would have to be an agency responsible for it's development and security. The moniker "EU certified" would require some sort of code evaluation and certification agency. As such it would become rather powerful.
I think it's a good idea, the OS would give the market a focus and allow for a collected development effort without excluding anyone active today from participating. Kinda like what I think Android was, without the risk of lock-in as it would be government funded.
The big question is if this would be within the current EU mandate, though.
I usually don't agree with "hardliners", but this one seems to have an agenda I can actually live with.
Literally...