I must admit i don't know how different US laws & officialdom are to UK ones, but over here a PO has no right to do that as an individual officer - conditions of parole would've been set upon release & if he's got a letter saying he's not under their area of jurisdiction anymore, then he can wave that in their faces while he's telling them to fuck off.
I would happily tell him to fuck off & if he wants to keep coming back then i would use your great American right to purchase arms to buy a gun, go to his house at night & shoot the jobsworth prick dead.