MechaPilot
Explorer
My problem is that her character's still alive, so she shouldn't be making a new character. I don't think it's unreasonable to only allow a player to have one character at a time. I mean, it kind of sucks for her, but that's the consequence of failing the saving throw. Letting her character die feels kind of the same as letting a character die because you rolled bad stats. It's not trusting the dice to make a good story.
I have a few comments and questions.
#1) Do you expect the player to still show up to the game sessions? If so, why do you expect that? Her character is, according to the PHB definition of stunned, unable to move of her own accord, unable to take any actions or reactions, is guaranteed to fail one of the primary saving throws (Dex), and "can speak only falteringly." This means the player will have virtually nothing to do with her character except to say, "I continue to lie there, I guess." Also, if the PC's Int remains at zero then the PC will literally be dumber than a pack animal and will probably not have much to offer through her limited verbal capacity.
#2) If swallowing is considered an action, reaction, or requires that one be able to "move" the character is already going to die of thirst in relatively short order.
#3) If the stunned PC is able to drink and swallow some kind of food, are the other PCs prepared to wash the feces and urine off of the character at least once a day? Do they have the water supply to do that? If not, I assume they're just letting her stew in her own waste, a scent that will surely attract scavengers and/or predators.
#4) Dice don't know how to tell a story, and they are quite literally incapable of doing so: they can only generate random outcomes. The DM turns those outcomes into a story, which is part of why doing it well is difficult. If it "sucks for her" you need to recognize that you are choosing that for her because the story can literally go in any direction that you want it to.