As said here not infrequently, are you willing to consider that your anecdote of n=1 may not be representative especially in a school for whatever reason generally not on a school’s radar?
My guess is that student also fared better and got more credit - in terms of relative excellence - than the students who made it out of the states but without national recognition in that same national writing competition. It’s nice to assume that the student entered that competition purely out of a virtuous love of writing and without regard to any effect that winning the competition might have on her chances of college admission. It would also be nice to assume that this writer gained such standout composition ability as you mention while strolling and not, as most professional authors I have seen speak, as a result of hours of reading and daily writing practice meticulously honing their craft.
The passage you quoted was about GPA, you mention that relative excellence in Poetry (another academic pursuit) is also potential advantage. Those two can’t both be true?