-Indeed, The Rubble was originally a mining station. However, the way you wrote it described it as a small mining station of which the Covenant attacked and a group of people escaped. You also said it in a way which indicated the Covenant attacked it while it was still a small mining station. Also, the plan was to get Slipspace navigational data from the insurrectionists, as well as functioning Slipspace drives, not just overrun the asteroid with Unggoy. They could easily do that with any asteroid.
-I agree with your second point.
-Spartans are expensive. ONI watches him, they'll put him off because he's acting all suicidal.
-At no point did you say he came out hurt, either. Your point is invalid. You wrote about it and then gave no indication of injury, nor did you write he was uninjured.

Zarkun also supplied an additional point. Sergeant Johnson was part of the ORION/Spartan-I project.

And good afternoon, Zarkun. ^_^