Why should I believe a scientific paper or textbook?
You don't have to believe it. If you choose not to believe the source,
that's fine, but we have a policy on what sources we consider
reliable. A few fans of a TV show is not on that list.
If you disagree with Wikipedia's definition of reliable, you should
try and get consensus to change it. Until you do, that's the
definition we go by, and by that definition, a scientific paper is
reliable, a random fan of a TV show is not.