And so the two things you listed were one person mentioning the spawn mechanic, and my venting that I didn't think my arguments were taken seriously, followed by actual argumentation which you left out? Neither are fallacies, one is not even an argument and the other is just a weak argument. Which I wanted to say is the fallacy fallacy, but then I googled it before and that isn't what the fallacy fallacy is.
To summarize my argument since it has been disjointed:
The ending monologue is a part of the game, and thus can be analyzed. People argue that we should not take it seriously because it is not literal within the universe, however for it to not literal within the universe, it first must be within the universe. If it is in the universe, that means that the player character is reading the dialogue/monologue. Because the player is reading the dialogue/monologue, that means that what they are saying is at least partially true: the player sees the game as fiction, and thus qualifies for having a higher tier key because he can create and destroy realms (which include separate overworlds, nethers and ends for each) as a whim.
If the player character isn't reading it, then we can consider the game of Minecraft and this story as functional separate, then the End Poem is a metanarrative about Minecraft, and thus contains the narrative of Minecraft within it. If it is separate, there is no reason not to take it as its own piece of fiction and thus power-scale it.
As for why we should disregard the author on this matter, it is because the principle of death of the author. In short, stories are meant to be experienced, not written. And thus each experience taken from a piece of work is equally valid, which includes the author's experience. It is not worthless, it is simply not worth more than what someone else believes. The work is final arbiter on what is true about the work. And the End Poem is a part of the overall work.
As for why we should power-scale it, because I heard that is what we do here. (This is a witticism. I am not very funny.)