Which contradicts nothing I've said. As nothing has been established that an elves lungs will automatically fill with water. Realism doesn't apply because it is a work of fiction. You keep trying to argue that we have to use real world "internal rules" for a work of fiction. That ignores how the author of that fiction creates any rules that they feel like and it not explicitly stated it is an unknown. It doesn't automatically become "real life rules". We can use "real life" to infer how something might work but that doesn't mean it is automatically the case if the author of the fiction does not give an explanation.
In the case of the show the writers established that lungs don't automatically fill with water. It didn't have to do so before hand because it did so during that scene. It is fiction and everything is created including those internal rules. So an author can create or change those rules any time the feel like it.