Can you retaliate against a prisoner -- someone over 18 years of age and not a party to a lawsuit -- who agrees to serve process on behalf of another prisoner? To put it another way, can a prison official who's served with a lawsuit filed by a prisoner permissibly throw the prisoner who serves that official with the lawsuit into administrative segregation for 60 days?
Of course you can. According to the Ninth Circuit.
Perfectly legitimate. Doesn't violate anyone's rights at all.