Thats only live coverage. Live coverage wasn't actually on the list in the first place. Deferred coverage remains on the list. The previous minister wanted to add live coverage of the 6nations and launched a public consultation on updating the list but as you say the IRFU and the 6 Nations council jointly lobbied hard for the opposite.
Its not the IRFU who awards the rights but the 6 Nations council. Obviously the IRFU have a say.
6 nations hasn't gone to subscription tv in any of the participating countries yet