She isn't exactly your normal person, all her insides are burned. Not to mention she heals fast.
And she didn't use the strain at MB because she liked/respected Venom, that much was obvious. She also did help those kids so there's that too.
So with the first part, are you saying that she assumed she'd survive because she had made the connection that no lungs = no self harm with activating the strain? Because that is certainly possible, maybe even likely, but it is also very possible she'd have no idea of the dangers, and her leaving Mother Base is partially based on her own uncertainties of the dangers.
I was somewhat pressed for time when I made the post so this was left unclear, but I know why she didn't use the strain. I was just stating that the game's given reason for her keeping the strain close to her chest (sorry) was because she apparently was uncertain if she wanted to use it for revenge.
My focus in my argument, and my point of confusion, is indeed why she wanted "revenge" at all? It seemed she had become pretty good pals with Venom and at least the kids, so I don't get why Codetalker even speculates that she'd want revenge. She was the aggressor back in the hospital, and Ishmael is the one who cripples her, what gives? Why is this even something she's considering, and I was trying to say earlier, even ignoring her good relationship with everyone, why would she be willing to potentially kill herself for some ill explained "urge for revenge"?
Why would she even be considering the option of revenge with a possible chance of suicide, and then, once she learns it can mutate, if she had even said to Codetalker that she would never speak English again,
and her apparent chosen option is exile and likely death,
why didn't she instead choose Codetalker's original "cure", cutting out the vocal cords? This is what I meant to convey when I mentioned the "real plot hole". Ignoring that she already shows body language and general ability to communicate through gestures (shower scene, when she interrupts Ocelot), why choose exile and likely death, when she can continue to exist as she had already chosen (the life of a mute, except with Codetalker) by removing her vocal cords and gaining people's trust by doing so. This sacrifice would probably exonerate in the eyes of most of Diamond Dogs, and she could live as she already planned to.
Why didn't she just ask Codetalker to tell everyone that she wanted to prove her loyalty to Diamond Dogs and show she wasn't a threat vector for the parasite by opting for the surgery, and living afterwards as she'd already chosen? It doesn't make much sense in my opinion for her to run off to die when this simple, already proposed solution existed in the narrative. It's drastic, but a ton better that death and exile, and as I keep on mentioning I'm this post, she'd already chosen to be mute.
Edit:
As for the game's other problems, (unsatisfying Chapter 1 with minimal story except beginning and end exposition dumps, practically hacked together Chapter 2, a bunch of themes and ideas touched on but hardly explored, lack of interesting boss
characters, needlessly droll Ocelot and apparently "angry since birth" Eli with no transition to the state we saw him in MGS1, Psycho plot device, Volgin being wasted, etc. etc.), I'd say Kojima on Konami are on an uncertain shared responsibly of either 40% or 60% to the both of them. Clearly budget issues got in the way of Kojima's ideas, but the amount of time for at least the story content we got is ridiculous.
I can't imagine the game would have been what I wanted (at least) given Kojima's own issues beyond budget though. I remember from a Yongyea retrospective leading to release that Kojima had said they'd wrapped up story cutscene motion capturing (not face) sometime in like April 2013, so I can't imagine the story was going to be massively larger if they had everything recorded back then.