Arnold underwent a shoulder reconstruction and sat out most of the 2014 season before joining the University of Canberra Vikings in the inaugural National Rugby Championship. He was included in the squad for the 2015 Super Rugby season. He made his debut in the Brumbies season-opening match against the , starting in their 47–3 victory in Canberra. , Arnold was among the tallest players in Super Rugby, behind South African lock JP du Preez at 1 cm taller.
