You can apparently only get the bot containers in the Quthor system for the Protector bots by taking on the Drengarian pirates. I got mine by saving just before the "passage" encounter and replaying it until I got the correct bot containers. After you have defeated the pirates and go in to loot the wreckage, it will not always give you a bot container and you may have to back out of the looting and "rerolling" the looting until a bot container drops. The lower percent survival (48%?) can potentially drop two bots and the higher percentage survival (71%?) will normally only drop one.
The last time that I ws able to get the protector bots, I had to go back to my save 4 times. At current point, I have been able to salvage 7 Protector bots and 2 of them had Gen 3 Military Precursor Cortical Cores. I was able to upgrade those 2 to over 90,000,000 credit evaluations. I could possibly get up to over 100,000,000 if I could equip them with elite oral, bondage, anal, special and vaginal talent boosters. So far I have only been able to get the elite boosters by buying them for 5,000,000 each from the Quthor space yacht, ( 1 potential encounter/day) Hardly seems worth it since we will probably have to start all over again next update.