Tiaral

I don't know. If this is irony, I don't see what's wrong with it... Moreover, the point is not so much in the quest steps, but in the logic of the people living here and their actions.
With the same success, one could say before eating the fruit: "Yeah, Revan specifically came up with some trick with a very long incubation period, immediately visible positive effects that increase immunity (so that later a person with improved immunity will still get sick), and it will be impossible to cure this infection, and healing potions/spells will not help, and all this is to give us an additional quest without a reward that cannot be refused. Nah, that's nonsense, let's just eat it." But the point is not that Revan needed something, but that the Mistwalkers had certain goals and certain means to achieve them.
And here I am considering their goals and means. And I see:
1) after the murder of Sharron, we are no longer needed by the Mistwalkers.
2) objectively, we are unlikely to be able to take revenge on them with the remnants of our squad (even at full strength, it would be unlikely).
3) during the unrest in the city, it is better for all valuable Mistwalkers to quietly disappear - there will be nothing special to do there anyway. Is there any point in deliberately staying to give them the medicine?
4) and do they even have a cure? You can assume that they were just lucky to find suitable fruits and mushrooms, but having a cure requires either a little more luck or deliberately spending resources on it (why? Only if it was needed for another operation, but definitely not for the sake of stupid mercenaries).
5) and finally, they have already deceived us. If they wanted to interact honestly, they wouldn't have messed around with the merchant, but would have simply approached us on the way to the capital and given us a quest. Slightly less honestly, they could have approached us, given us a quest, but then deceived us and not given us a reward. The fact that the Mistwalkers chose to manipulate us with the fruits shows that they don't care about any promises, collateral damage, and so on. They don't care at all. Therefore, they need at least a minimal reason not to screw us over - based on what I wrote earlier, I don't see it.
That's what I was guided by. If there is a flaw in the logic, please correct me./