You have a problem of differentiating unavoidable and unavoidable that happens all the time.
That’s true, there should be no difference, but either way, you seem to have missed the word “occasionally (lif’omim)” which means it doesn’t happen all the time.
Could you clarify this paragraph -I don’t understand your point.
I’ll try: The M”B says that there is more reason to be machmir on hanaah from food, because one has a strong desire for it, than from other types of hanaah.
Who says there is no other fire available? And who says this was the main dish and there would be no main dish? In other words, again you are assuming this to be a case of Tzorech Godol -who says?
It’s not 100%, you’re right, but in most cases, the fire going out means no cholent.