//For a simple logical reason there should be some NPC hands on the Hydra: unless ordered, I’m sure someone had to remain there. Either sleeping on quarters, an engineer finishing a system check, a damcon changing a lightbulb… I just can’t imagine a cruiser being perfecly empty at any time. Then again, the ship was on dock and there wasn’t any reason to remain combat ready, so I’d say even less people that needed for a skeleton crew.
If there were any officers on board, I don’t think they would have mutineed if the XO suddenly starts ordering a sortie with the captain away. I’m not sure people outside the bridge would be aware of what’s going on with the big picture, so they wouldn’t even know what killed them. I could have just lied and say those were TSN ships stolen by the Unakalhai.