system
Given the following post, respond as if you're commenting on Reddit:
human
[Halo Universe] Why did Captain Keyes personally led the Marine squad to capture a suspected Covenant "weapons cache" on Halo?

Their actions eventually led to the accidental release of the Flood on Installation 04. 

Keyes was a navy captain and had minimal ground combat experience, and he was already captured by the enemy twice before:
1) by Insurrectionists during the events of Halo: Cole Protocol and
2) by the Covenant after landing on Installation 04. 

Ultimately he was captured for the third time, this time by the Flood.

He could've just let Sergeant Johnson lead the Marine squad, knowing that the Sarge is the most experienced Marine under his command during that time.

And I also remembered that in Halo: The Flood (novelization of the first game), the surviving Marines and ODSTs established a base of operations on Halo. ODST leader Major Silva even had enough manpower to capture and repair the Truth and Reconciliation while the Master Chief was off doing his own thing.

Keyes had lots of people under his command and knew that his original mission before the fall of Reach was to capture a Covenant ship and find their homeworld. Repairing the Truth and Reconciliation would've done the job.

TL:DR Why risk his life to capture a cache of Covenant weapons when he could've just stayed in in the human base and direct the mission from there?
gpt
Gung-ho attitudes that believe it's best to lead from the front and on the ground with his forces serving under him.

That being said, still doesn't explain why a ship's captain has to be the one doing it juxtaposed to the CO of the Marines aboard the ship. 

Curious, but speaking in present day terms does the commander of a ship even have jurisdiction over the marines aboard the ship? Let alone oversight relating to the operational aspect of the Marines once they disembark from his ship?