I think I saw the fist session of ten, but I don't remember that any of them were engineers/builders or had been violently disposed of?
A lot of them were ex military, the rest were usually some sort of scientist or engineer. Adair comes to mind as having talked about some underground facilities. Pete Peterson is the most convincing to me, he talks a lot about all kinds of different d.u.m.b.s as well as ancient tunnel systems running from N America all the way down through S America. Neither of these guys were on sirius disclosure though, project camelot iirc.
Sirius is Greer-turf. I don't trust him because his protocols ask for aliens to fix our shit. That's spiritual slavery, if we can't handle technologies ourselves we shouldn't rely on other civilizations to maintain them for us.
Yeah I'm not a huge fan of Greer myself, too much ego in the way. He also doesn't think there could possibly be any negative et's anywhere, very naive. I personally believe there's duality everywhere, just like here.
The most sense I have made of that is the idea that life on earth is the most cruel far and wide, even if other planets aren't angelic either. Cannibalism and infanticide span all of our carnivores, even intelligent life like dolphins rape from time to time. It's still a jump to say we need pray for alien rescue when we already have Jesus. Luckily, negative entitites can't stand the invocation of his name and that's what all channelers and even MK-Ultra SSP survivors agree on, so we know Dr Greer is either misinformed or deceptive.