Thomas joined Crusaders in March 2010 on an 18-month deal. He made his Crusaders' (and rugby league) début against French side Catalans Dragons on 19 March 2010. Thomas was concussed seconds into his rugby league début after a heavy challenge from Catalans player David Ferriol, and as a result had to leave the field after thirty minutes. Crusaders went on to win the game 14–6. Thomas went on to score his first try for the Crusaders against Wakefield Trinity in a 20–10 away victory on 11 April. A groin injury prematurely ended Thomas' first season in rugby league, but his recovery was hoped to be complete in time for the 2010 European Cup, for which Thomas was selected in the Welsh preliminary squad.