I agree with you, that a sprint goal has its own purpose, but I am sure, that I don't write the sprint just as a repetitive task to get rid of backlog items.
The backlog gets updated and changed via the Product Owner during the sprints.
What I don't get from your post is the link between emerging work during a sprint with an emergency happening and therefore a missed sprint goal. What does this have in common with Scope Creep?
Scrope creep describes the fact, that a sprint is fixed and not that the backlog is frozen during the process.
"Consequently, the Sprint Backlog is updated throughout the Sprint as more is learned."
This phrase is right but does even prove your exclamation as wrong. Adding work during a sprint into the backlog is an entirely different case than adding workload on top of a sprint.
Maybe I made that not explicitly clear in the article. With backlog, I don't mean the sprint backlog. We may be talking at cross purposes.
"As the Developers work during the Sprint, they keep the Sprint Goal in mind. If the work turns out to be different than they expected, they collaborate with the Product Owner to negotiate the scope of the Sprint Backlog within the Sprint without affecting the Sprint Goal."
Even this passage is affirming my scope creep flaw. When everything is going into the wrong direction and your team finds out the sprint is overloaded, but you are able to negotiate everything except the sprint goal, then how do you even react to sudden changes or emergencies? I am convinced the sprint goal won't be "Make new hotfix" or "Stakeholder A wants blue colors immediatly".
In your last passage, you've said it right: "[..] as long as you meet the single, coherent Sprint Goal." And here it is: What is the Sprint Goal? Who does set it?
Scrum states to have at least a deliverable increment at the end of a Sprint. Whenever the team is not able to deliver because of misconception or other problems, then there is no flexibility inside. How could it be? The Sprint goal is endangered and therefore anything else is set to non-important besides the Sprint goal. Tell me now, where is the flexibility?