Of course I'm self indulgent. the joking idea I've come up with for why he would end up hanging out with junior researcher Persica (the new sona's name) is that Star Command gets convinced to try out a rehabilitation program, putting villains to work in constructive environments. Nos would be a huge problem considering his ability to build and control technology and his tendency for backstabbing, so they just... drop him at a random Karn research station with this morbid weirdo where there's minimum damage to do.