Flournoy and Kevin Goecke, 38, also from the Sebastopol area, are charged with misdemeanor resisting arrest. Goecke also faces a charge of public drunkenness. They were in court Thursday, where their lawyers sought information from the officers' personnel files.
Both men declined to comment. A jury trial is expected early next year.
Police Chief Tom Schwedhelm referred calls seeking comment Thursday to Lt. Craig Schwartz, who said only that an investigation was underway to determine if officers violated any laws.
Assistant District Attorney Christine Cook also declined to comment.
The incident took place in the evening after the Handcar Regatta, which drew 12,000 people, including hundreds of "steam punks" dressed in Victorian era garb.
Flournoy, Goecke and another friend, Jeffrey White, were among them.
Flournoy, a former mortgage broker, is a West County artist who helped create the Easel Park theme camp at the Burning Man festival in Nevada's Black Rock Desert.
According to a police report, Officer Diaz was dispatched to the Last Day Saloon on Fifth Street at 9:23 p.m. to check on a report of an unwanted subject dressed in a top hat and tails, later identified as Flournoy.
A saloon manager, Dianne Torres, said Flournoy had been kicked out earlier for pushing an employee, returned and refused to leave. Flournoy was gone when Diaz arrived.
Diaz spotted Flournoy a block away with the two other men and attempted to question him, ordering him to sit on his patrol car bumper. The officer said Flournoy was confrontational and his friends kept moving closer, yelling comments.
At one point, Diaz said Flournoy leaped to his feet and faced him, apparently in reaction to White, who had begun filming the encounter. Diaz grabbed Flournoy's arm and forced him onto his car, calling for backup as a crowd gathered.
"I heard someone yell out from my backside, &‘There's more of us than you,'" Diaz wrote in his report.
Officer Jonathan Crespan arrived first, detaining Goecke and White. Seven other officers responded next, including two sergeants.
Diaz said Flournoy wouldn't let the officer handcuff him so Diaz punched him in the right side of his face twice. Diaz said he punched him again in the back when Flournoy concealed his hands underneath his body and hit him four additional times in the left side of his rib cage.
Diaz said Crespan and Sgt. Mike Heiser helped him gain control of Flournoy, who was charged with resisting arrest.
Flournoy was taken to Sutter Hospital where a doctor diagnosed three broken ribs. He was booked at Sonoma County Jail early the next morning and has since been free on bail.
Flournoy maintains in court documents that he complied with the officer's orders and the response was unreasonable.
Also, Goecke accused Officer Crespan of punching him in the chest with a martial arts-style "palm heel strike" and then grabbing him by the hair and shoving his head between his legs.
The men have asked for a dismissal on the grounds that the officers' conduct was "outrageous and inexcusable," violating their due process rights. In court papers, Figueroa said the action amounts to "summary punishment."