It's not considered an exploit. They said it was fine to do last week. I wouldn't mind if they keep it like this since they nerfed the credit payout. It's a good way to gear up while lvling and a good way to lvl.
This really needs a solution ASAP. It's a limited time event and time is just being wasted now. The cannon being added to the life day vendor instead of the snowball seems the simplest solution.