Retired NYPD Sgt. Sean Cameron is in the fight of his life, against not only the 9/11-related cancer that has ravaged his body, but with the city, which has denied him a disability pension. The Police Pension Fund last month denied the retired cop’s request for a 9/11 disability pension, saying they can’t confirm Cameron spent the requisite 40 hours at the World Trade Center site needed to get the pension.