The real problem, in Victoire's mind, was not that Hui had died (of course the problem was that Hui had died. Hui, and Lambert, and Fisher). No, the real problem was that Hui had died in the exact same way as Lambert. An illness, respiratory, blood in the saliva, struggling to breathe. Exactly the same.
Now Victoire is an astrophysicist, yes, but it wasn’t her only interest. She loved the stars, and physics, but also 19th century authors, and gardening, and when she was in school, (secondary school, not university), she maintained a casual fascination with viruses, enough to consider, but not pursue, a career in virology. She understood disease transmission vectors enough to know that an airborne or waterborne virus wouldn’t go unnoticed, as Rhea was in charge of the air and the water, and neither would just strike down Hui and Lambert and leave Victoire and Lovelace and Selberg alone. A blood borne virus was rather unlikely to do that as well, unless Lambert and Hui had accidentally swapped blood, which Victoire was reasonable enough to accept could have happened without her knowledge, if she had perhaps lost several days of her memory, or perhaps alien technology had healed a wound before she knew about it, or perhaps the entire Hephaestus station was just an elaborate fever dream she had been having all along and she had never left Earth at all!
The last natural transmission vector on a tightly regulated ship with no bugs or small mammalian lifeforms that Victoire could think of, a sexually transmitted virus, was even less likely, as she and Hui had spent plenty of covert hours together with doors locked, and Victoire was perfectly healthy, as far as she knew, thank you very much.
Which only left...
If she's right, and she’s rarely wrong, then the problem is not that Hui died. It’s that Hui was intentionally infected. Which leaves three suspects in Victoire's mind (four if she allows for the possibility of Lambert being far more monumentally stupid than experience suggests):
1. Either Rhea had subverted the directive that prevented her from killing crew members. or
2. Everything Lovelace ever said was a lie. or
3. Everything Selberg ever said was a lie.
and Victoire knew who she would pick in a life-or-death situation. Isabel Lovelace was sarcastic, and chaotic, and tough as steel girders, but she’s sincere. Honest. Victoire witnessed her reactions to Fisher's death, and Lambert's death, and Hui’s death, and she knows self-blame when she sees it. (She would know. It’s only Hui’s last words to her that kept her from putting herself on her list of suspects. Don’t blame yourself, Vic. Keep your chin up.)
After everything she has accomplished, after a lifetime of studying and ambition and successes and failures that turned into successes, Victoire thinks it is the height of irony that she finds herself wishing she had taken time to watch more movies. In particular more Bond films. Conducting a covert operation of subterfuge and intel gathering, while simultaneously trying to modify a VX engine to propel a lifeboat through 8 lightyears of deep space, while simultaneously trying not to be caught doing the aforementioned covert operation by a man she strongly suspects has had his fingers in the mother program and biological terrorism (and who knows what else), is not exactly in her toolbelt of skills.
She’s right. Selberg catches her rifling through his lab files when she is supposed to be welding the VX engine together. She hopes Hui can forgive her.