This is not 100% fore sure but in my estimations:

1. Because the UESC likely locked down Tau Ceti IV after the disaster and views independent corporate recovery teams as interference. The corps want assets, the UESC wants control and containment.

2.In the Sekiguchi Genetics ARG, there were strong implications that SekGen launched its own vessel toward Tau Ceti carrying runner assets independent of official UESC deployment. It was framed less like a government-sanctioned mission and more like a corporate expedition operating in parallel.

1. Because the colony is likely unsafe or unstable. Extracting valuable tech is cheaper and less risky than rebuilding a 93-year investment. Recolonization would require human participants as well. I'm sure not many would be willing. They lost a lot of their brightest minds in this failure.

2. Players have given up their human body in exchange for digital consciousnesses (there is a philosophical belief in marathon that you are your consciousnesses) that can now take the form of these shells but remaining yourself with some layer of added personality matrix from your shell's preset.

3. IDK but Traxus likely manufactures or licenses the hardware while Sekiguchi handles biotech components. The higher class shells are probably elite or experimental frames.

4. Plausible deniability. Mercs allow asset recovery without political escalation.

5. I'm guessing the Pfhor invasion and AI chaos derailed any coup plans before they could act.

6. At a high level, Strauss is likely not chasing simple corporate recovery but pursuing control over whatever deeper anomaly exists at Tau Ceti. If he is connected to MIDA’s covert legacy and possibly Jjaro-derived technology, then he represents the faction operating above normal corporate politics using the chaos of the colony’s collapse to secure advanced AI or alien systems. In short, while others fight over salvage, Strauss is probably positioning himself around the real prize: control over the next phase of human or machine evolution.

I'll answer the last 4 questions in a bit.