Had the same thought, especially, while reading through the Galnet articles about the Antares
However: Don't mix up the FSD "Modes". Supercruise is like the Warp Drive in Star Trek, while the Hyperdrive is more like Star Wars / Stargate.
Supercruise is based on the Alcubierre Drive, which - as you said - shifts the frame of space so, that the space in front of the ship is compressed and expanded behind the ship. Since there aren't different "folds" (the folding is "fluid"), it doesn't move forward with the thrusters. A good analogy would be a current in a river. The Water around moves and pulls you along - in this case, the Frameshift moves the frame of space the ship is in, like pulling on a rope, while sitting in a boat. Supercruise relies on Einstein's field equations or general relativity - so, pretty normal physics, nothing especially fancy, since it doesn't involve Quantum Mechanics (see Alcubierre drive - those are "real" theoretical physics).
https://upload.wikimedia.org/wikipedia/commons/thumb/c/c4/Alcubierre.png/800px-Alcubierre.png
Hypercruise on the other side punches a hole through space - it's a wormhole. How this exactly works, is open for debate, at the moment the theories range from Quantum Foam, to Dark Matter over to the Quantum Field Theorie. How you would determine entry and exit point of the wormhole is a completely different matter. I've read Stephen Hawkings "Universe in a nutshell" countless times, but i still haven't fully understood wormholes, or at least how you could control them. But, since apparently Wormholes are inherently unstable and they need to use "exotic matter" to stabilize them, this ties in very well with Elite Lore:
In Elite Lore, the first long range "jumping" started around 2800, with so called "Faraway Orientation Systems Controllers" - they had defined entry and exit points, so the "Wormhole" was kept open and were not generated by the ships.
By 3125 the first hyperdrives for ships started appearing - they used so called "quirium" as exotic matter to stabilize the Hyperspace Conduit and were "Type 2b Hyperdrives". Only the "Galactic Cooperative" had the "recipe" for quirium. However, the Galactic Cooperative took it to it's grave, and these "small" Hyperdrives where lost until 3290. We all know what happened to the Prism System because of Tantalum - the new "exotic material" (at least, that's my guess). They are called "Type 3 Hyperdrives".
Another guess of mine is, that the Antares used something like a "2c Hyperdrive". We also know, it is possible to stay in that Hyperspace Conduit or "The Space between the Universe" - Thargoids have to power and knowledge to use that. We also know, the Guardians appear to be extremely sophisticated. I wouldn't be surprised, if they have mastered all of this too.
Maybe those expeditions were for a combination of the "Faraway" travel and "2b Hyperdrives", so you could jump from the bubble to somwhere in the Formidine Rift in a matter of seconds, to establish these Orientation System Controllers out there.
Also, since Drew Wager seems to be as fascinated by those theories, as i am, i'd say it is not a very far stretch, that all this, the Formidine Rift, Sirius Corp., Salomé and so on have something to do with Hyperspacetravel, Witch-Space (or the Space between the Universe - some actual scientists have theorized, that this is some kind of quantum level) and maybe even another species, living inside that realm - maybe the Formidine Rift is some sort of very special part of space, where these edges are not as constant, as they are anywhere else (AFAIK, this was suggested somewhere...).
This brings me to another speculation...has anyone every looked for black holes, anomalys or anything else around there? Especially, since apparently you can find the mystery for quite a long time now...
(Edit and Disclaimer: I am just a very big Sci-Fi Nerd, i love science and i tried to study something that had to do with all this - but i dropped out after the third Semester, i'm just to impatient for the maths behind all that stuff...i may be wrong about the Wormhole Stuff. As i said, i haven't even fully understood the real theories behind them. So if we have some "real scientists" around here, that understand the Science behind the Wormholes, i'd love a correction of things that are wrong)
This was awesome, and VERY interesting, and you are right, and I knew this
Been transitioning over to night shifts and my brain has been a bit scrambled [wacko]
So running with wormholes (hyperspace/witchspace) instead, i think this actually fits my theory even more. An area of space and time we are not meant to be, and it's getting noticed... The news today of a disfigured body in COL70 is interesting too, especially after learning Wreaken construction is tied to Sirius also. A secret base where these experiments continue? explains the high radiation and high security.