The post in Qn, should neither be tagged with scripture nor with mythology.
scripture should be used iff, the Qn specifically expects or discusses a scripture. A very good post has been initiated by @SreeCharan for the awareness on this topic:
Are we correctly tagging "scripture" tag?
Now, mythology# is not appropriate for this post, because it implies that MahAbhArata present in sacred-texts.com, is a "potential myth" if not a "complete myth". This book is revered by many people across the world and within the site. It should not be termed as a "myth".
One should use this tag only when dealing with "mythology" based sources. However, as of today it seems that we need to define which scriptures belong to "mythology".
# mythology - collection of myths, especially one belonging to a particular religious or cultural tradition.