Is the thematic relevance of episode 8 just that the show spoke out against his methods or did you mean something else?
Yes, but episode 8 is also relevant in other ways. Volume 4 of the LN makes this a bit clearer, but there are strong parallels between Rumi and Yukino's personalities. Rumi's situation was very much like Yukino's past (which Hayama was also involved in). The conflict - and the fact that Hachiman never truly resolves the conflict - points to the fact that Yukino and Hayama have never really come to terms with their past. Everyone is still a work in progress.
