I just tried to do a public event on Nessus of that Servitor Version. 1st small Servitor spawned, I killed it almost instantly with my machine gun (AI was literally dead in 1,5s) and then the Boss Servitor of the public event didn't lose the immunity shield. For the entire remaining 3,5 minutes of the event time. Needless to say the public players were pissed about me. The gun I used to kill the Servitor was an Adept "The Swarm" with Bottomless Grief and Vorpal+ Adept Big Ones mod slotted.