Is this not a false dichotomy? Unless you are purposely using deprioritization as a substitute for blacklisting it would stand to reason that results 'moderated' to the bottom of the a priority list ended up there because they actually aren't considered useful/relevant to the query. So unless you are moderating in bad faith blacklisting is clearly different because it removes the users ability to find the content at all and it wholly ignores the intent of their search.
