I agree entirely with your tutor, but there are two completely different meanings of "critical analysis". If you say "critical analysis" most people take that to mean expressing an opinion. It can also mean using the materials at your disposal to analyse the facts. The second interpretation is wider because it includes using journal articles and cases to determine what the law is.
I think your tutor has taken the latter interpretation. Your notes say that coursework is not the place for formulating your opinion, obviously this depends on what the question is but its certainly true for problem questions.
Much of this is common sense: you need to answer the question, not use random stuff just because you happen to know lots about a different but related question. Its very easy for people to fall into a trap - if you know lots about something that isn't really relevant but not that much about the question, or the question is difficult, its very tempting to answer a different question. In my view you can't go far wrong if you clearly and accurately answer the question.