Scott Spruce, of Pendoylan Close, Barry, was due to be sentenced at Merthyr Tydfil Crown Court, today March 7.
However, sentencing has been postponed due to Spruce refusing to leave his cell.
Spruce pleaded guilty to assaulting a police constable in Barry on December 24 last year.
He also pleaded guilty to inflicting grievous bodily harm without intent in the town, with the incident occurring on the same date.
Spruce, 49, submitted his guilty pleas at Cardiff Crown Court on February 13.
He will next be sentenced at Cardiff Crown Court on March 10.