I don’t agree with your actual criticism.
First of all, you seem to have misunderstood how the plague dispatch (maybe you miss some part of the lore because of your choices?). However it’s true that it’s not us that can dispatch the plague, but anyone that had been infected by it.
Or do you mean in the lab? Then effectively were are the only that can dispatch more of the plague to corrupt the remaniant of the city (or to try to find a cure for it) since we are the only one to have access to it.
As for being the only one able of “corrupting anything” because of our own unique capabilities, many – like myself – don’t like that, so I think it’s good that this game is not about that.
That said, if you like games like that, there is Corrupted Kingdom and many other like those I seen you have comment (Echoes of Home, Crossworlds).
Finally, about the “conservative or naive” part, I think it makes sense for those that succeed to not fall to the plague, as the MC itself (well, again, depending on your choices).
So, I don’t think there is anything to remove the narrative. Review it and fixe some grammar error, yes, but removing anything, no.