We'd like to think, "here's video and physical proof this creature is running around killing us!" is a legit defense against that chick's death but we saw the company director straight up murder a dude who asked a question with not a shred of concern and in another chapter the scientists mentioned that chick got pissed at a researcher and stuffed his living brain into a jar with his eyes still attached because of some perceived slight or failed results. This is literally a lose lose situation for almost everyone in power aboard the ship. That's why the pirates are a power play to distract, the company can still find fault with them for the pirates but the captain can try to disappear in the chaos or push blame on shitty luck and the dead leaders and hope it deflects enough. One creature on the ship running around killing your entire command structure is straight up not going to fly. Even in the current military of any nation which adheres to some logic if a squadron lead gets their men decimated to a small force due to being caught unawares there's going to be some fallback on why shit wasn't done this or that way and some heads will roll. In this universe company exec's are at worse Nobility at best emperors that do whatever they want so their whims are literally unpredictable to us but given the context so far it clearly leans sociopathic.
Scientist #13 walking into the lab room does win darwin award of the hour ofc, no reason to be wandering the ship with a single guard if you know shit is going down but we don't know if the current news of MC's slaughter has effectively traveled yet as shit is moving fast and most of the leaders of the ship are down which brings into the problem of time's passage. We can assume a few days since MC has hatched but due to no real time table at best the last couple chapters where MC cleared house and this chapter aren't all that far apart time wise which is likely as the cleanup crew is still working on the bodies when captain picks up the plasma pistol.