This is the question: Thumb position when soloing (or performing scales) on electric guitar
I don't believe the referenced answer was particularly relevant to the original question, but I've edited it clarify even further nevertheless.
Is there a process to request it be unflagged?
Typically you can just make the edit, and it will automatically enter a review queue for people to look at it again. If it's not getting attention you can flag it with a custom reason and explain the situation. If you still get nowhere and feel strongly about it, coming to Meta is the right thing (and ultimately fine in this case too).
Once you edit a question, it automatically goes into the reopen review queue. Your question is currently in the queue to be reopened right now. Whether it will be reopened or not will depend on if the community feels like the question is not a duplicate and is sure nothing else is wrong with it.
As a side note when editing a question due to being closed, make the edits to improve your question not make meta arguments to get it reopened. Looking at your edits I see two paragraphs that are meta only and I've removed from the post:
EDIT: This question has been marked duplicate, but I don't find the referenced question and answer at all satisfactory! It simply restates the same general answer that I've seen everywhere else. So let me try to augment or restate my question as follows:
Also, the other answer speaks mostly to playing chords, which to me seems very clear for thumb behind (especially for barres). I'm specifically interested with regard to soloing/scales. It seems that in that case it might not be so clear-cut, which way is better.
I also suggest editing your original question to reflect what you have added.
