It would give Virgin access to an AOC (or if you like official clearance to fly) as they would more than likely use Impulse's current one. Would only mean getting clearance from the authorities on the airworthiness of the planes they want to bring in, rather than having to go through the whole fine toothcomb checks that the authorities do to any new start up. I really can't see if Virgin need Impulse for any other reason, and Virgin's announcement would have sounded the death knell for any float/revenue raising that Impulse would have done for it's rumoured expansion into mainline flying.
Apart from all that, a merger would be excellent for one reason - dare I say it! You could probably get away with telling the other half that you were going to the airport to ride a Virgin on impulse!! (Or an impulsive Virgin !!!) LOL !!