It's been operating for a matter of months...
That excuse won't wash with the bean counters. The only way it would stay is if the airline have real confidence in the route and such poor loads isn't going to help. UA will redeploy the 752 elsewhere. It's an easy target for cancellations as other routes would cost significantly more. They would likely make more money have the aircraft on standby for the whole summer than what it does going o NCL.
If it manages to survive all it will take is a spike in fuel prices to end it.