Yep.
For the benefit of those who weren't around for it, the original hypothesis that it was Guardian descendants (this includes AI just to be clear) that Halsey had encountered was based on extrapolating out their development, and noting that the only thing that had been reported/encountered which was a potential match was what Halsey had described.
For anyone who wants a more detailed explanation, here's a link to a post I did on it:
Greetings Commanders, Issue 10 of Sagittarius Eye is now available. Our team of talented writers, designers, artists, and editors have been hard at work again to provide you with fascinating stories right from the world of Elite Dangerous. In this issue, learn about the history, cultivation...
forums.frontier.co.uk
(For reference it's not a post that was written as an explanation as scratch. Rather it's a response to a Sag i article in which the hypothesis got misrepresented. So long as that's borne in mind when reading it should still make sense, and provide a reasonable explanation.)
As a mild aside, I'm not sure that we can actually say that we know that the AIs turned on the Guardians to ensure their own survival. Strictly speaking it's just something that Ram Tah hypothesises (in log #10). Later logs make clear that the military AI were against it and the civilian AI somehow compelled them to act (specific quote: "The military Constructs were opposed to this decision, but somehow the non-military Constructs won out, forcing their military counterparts to comply with the attack."). The last logs also makes pretty clear that the civilian constructs had been relegated to a position of permanent menial servitude in Guardian society, which IMHO is likely to have been one of the most significant factors in their turning on the Guardians.
I wouldn't be surprised if there transpired to be some very early Guardian-Human contact, though I kind of hope FD haven't done that. I would say though that IMHO it's almost certain that this isn't the first time spacefaring humanity has come across the remains of Guardian civilisation in some form or other.
I also concur on the likely Raxxla connection. I still hope that FD haven't gone down that route though and are doing Raxxla as a completely separate thing in its own right.