Eneas did not know what he was going to find in Argos; he chose a raid team with seasoned soldiers, engineers, and medical personnel. Although it was a small team, they could not leave aside surveillance of the perimeter for what might happen.
The opening hatch closest to the bridge was unusable, and on their way inside the Argos, they had to make their way through many secondary corridors, areas without oxygen or gravity, or doors and bulkheads closed tight. It was a tedious operation.
If there were officers alive behind the bridge door, they must have already detected the incursion, and if they had been subjected to a bloody pursuit, those who remained must be armed and prepared to repel an enemy boarding.