You know, I skipped quite a few pages, but there's another possible reason why there's fission research.
Those guys are building a navy, right?
For that, they need eezo.
But they may also need eezo for fusion missiles.
However....we, in real life, use nuclear fission to generate a fusion reaction in our nukes.
EDIT: What's concerning is that we can detect the fission reaction happening while in outer space.
A properly shielded nuclear fission reactor gives off background level radiation, which means to detect it, you need sensors inside the reactor.
The fact that we can pick it up on the outside might be why they're shuttling people in and out.
They're exchanging long term radiation exposure for short term radiation at a higher cost of fuel and supplies.