Again, it's not about the lack of planning ahead. Say your fighting a really hard boss, you didn't expect it to be this hard. All of your healing option have been used. You can't do a short rest in the middle of battle but have some food. Why can't a DM allow that? What rule is there that says you can't do that?
The rule (if you need the rule here) is "food does not restore your health" and "eating full pig's head takes longer than a bonus action". But 99.9% DMs and playes would have enough common sense not to even ask for such a thing.
I'll repeat my post that you cited but probably did not read: "... you get prepared and you fight or you run away and return prepared next time"
