Digwa has also applied to appeal against his conviction for murder, which will be decided separately.
The 23-year-old was also sentenced for carrying a knife in public.
After stabbing Nowak, who came from Chafford Hundred in Essex, Digwa lied to police that he was the victim of a racist attack.
The case later sparked protests after police body-worn footage was released showing officers failing to give Nowak first aid and instead handcuffing him as he lay dying, despite him telling officers he could not breathe.
The Independent Office for Police Conduct previously said it was investigating two officers for potential gross misconduct.
Twelve police officers and a police dog were injured during the protests in Southampton on 2 June.
Demonstrators gathered outside the city centre police station before moving to an area near the Digwa family home and the murder scene.
More than 30 people have so far been charged with violent disorder following the incident.