Actually, come to think of it, I think it's almost exactly accurate that "He had the same seniority in the same role that I would be have today if I had not quit that company 4 years ago." (This incident would have been from 5 or 6 years ago.)
>that Z should be allowed to "continue to devote his full attention to work which he is well-suited for."
So what was this work? What did the person saying this have in mind?
(I cannot possibly imagine anyone saying that with a straight face, if they meant that he is totally incompetent but is the boss's son-in-law. If your quote/paraphrase is anything near accurate, the person must have genuinely thought that z was making an excellent, albeit different type of contribution. He took time out of his day to tell you that. What could he have been 'well-suited for'?)