Just to clarify something: There is no such thing as "self-plagiarism" just like there's no such thing as "self-escrowing". If you copy/paste or repost something that you, yourself, have written it is by definition not plagiarism. So please, let's stop repeating this meaningless phrase.
Although I'd love to agree with you, my university sees it otherwise, and if I ever want to get my MD, I do have to dance to their tune.
However, even if we call it a different thing, the definition would fit just right in this context: "Quoting you own work over and over again in order to get more citations" (or in this case, merits).
In this case. I agree with you that self-plagiarism is appropriate word since the accused a recycle statement from his old post just to answer similar topic as if it was new a post from him. He is not obligated to answer all question here especially if it's similar to bunch of old thread.
Good thing that this was brought up by OP early before the accused abused this kind of scheme until he rank up. @Shamm is good poster based on the content of his post, he can get merit on appropriate way.