Okay, okay hear me out. Canonically, it makes sense when you put thought into it. They see themselves as the only Kiith of a ‘higher breed’ so to speak, claiming to be the only ones that really came from elsewhere in the universe. They have a deep disgust for the other Kushan factions.
And what about their origins? Their sigil is the only one of the major clans not on the Khar Toba or the rock carvings we’ve seen. Hell, even the Soban, supposedly the most recent one, had theirs on the wreckage. That may be a minor oversight, but maybe they just co-opted it from history. The Siidim are also one of the two clans who remember the most about Kharak history, meaning they likely were around from the beginning much like the Gaalsien. But then why are they not then using a sigil that’s been around from the beginning? I think that was intended, but I didn’t write the lore so I wouldn’t know.
Then think about how this would have come about. I find it unlikely that the prison transports weren’t at least checked up on from time to time by the Taiidan during their voyage if not having the prison transports under direct Taiidan control, even. That one’s maybe a bit out there, but not implausible. And after landfall, I can see the Empire wanting to MAKE SURE they stay put. Orbital debris of all sorts can be found around Kharak. Sure, maybe most of that debris is from the Core messing with shipping lanes, but Kharak is waaay out in the boonies galactically speaking. Not much passing through there in the first place. Maybe some of these ships were Taiidan imperial vessels that acted as escorts and once seeing the harsh condition of their new home decided to attack using belligerent and dangerous methods, including smashing prison ships into them as sacrifice, forcing down some of the guards along with them, or maybe once the Hiigarans reached the world, planned to turn on the Core immediately to strand their captors and prevent news from leaving of their arrival and subsequent attack.
We also know that Kharak has hundreds if not thousands of unexplored wrecks littering the surface. Some of them could be downed taiidan ships just as any of the other previously unseen factions we were introduced to. But of course, these stranded Taiidan wouldn’t want to let the locals KNOW who they are for obvious reasons, and kept their heritage secret.
And this is all without even needing to bring up the Torin carrier, as I believe canonically that one has only been there for centuries as opposed to millennia. However, what CAN explain it is the Siidim sending a standard light-speed signal off towards the galactic core to hopefully tell anyone listening what’s going on. Give it a few thousand years, said signals might have finally reached an outer-rim outpost and been picked up, resulting in the Torin carrier being sent to investigate / deploy an orbital weapon platform to hopefully be used to stop Kushan progress in a fast way should they see a need to down the road.
But why would the Empire then abandon their people down there, you wonder? Well, I wouldn’t put it past a decadent empire to do. After all, any mention of the Hiigarans would likely be forbidden. Any effort seen going to the system would be legitimizing a former foe they’d rather see extinct. And the people caught in the middle aren’t worth it. So the Empire “forgot” about these stranded Taiidan over time, and eventually actually might have. Or covered it up, while contracting the Turanics to play watchdogs instead, not wanting to sully their hands.
Then there’s the Sakala’s encounter with Rachel at the crater to look at. Was it really all about a religious zealotry, or was it them not wanting any surviving witnesses to the truth at the site? Maybe a panic about the secret getting out? After all—if Kushan kind found out that the Siidim are in fact descendants of those responsible for putting them on literal Hell all this time… I could see the Heresy Wars making a comeback in a real way.
And to conclude these mad ramblings, I’d also like to mention that this all plays part in a secret project I’ve been working on outlining: an as of yet untitled Deserts of Kharak fanfiction set over the span of thousands of years of Kharak history, all taking place before and leading up to the first game that started it all. Of course, don’t expect anything to come any time soon as my schedule is a bit full at the moment, but I might be able to free myself up some time in the Fall to at least start.