They are, but that can take months to process for a serious injury. Under General Municipal Law 207-C (state law), police officers injured in the line of duty are to receive their first party benefits, i.e., payment of salary, wages, medical and hospital expenses while they are out. NYC is the only municipality that has it's own line of duty system.
If you are in the NYPD and the same injury happened, you would be covered with 100% pay and benefits. These guys get nothing. I believe the NYCDEP PD is looking for equal treatment/protection more than anything.
I can't fault them. Even though these guys wear a uniform, shield, and gun, the city doesn't see them as police officers I guess. IMHO, if you are wearing a uniform, you represent authority and are a target. I wish them luck.