The idea behind 95 ATAR was to compensate for the inherent flaws of it. E.g. the school you attend can significantly impact your ATAR. Some people don't live in areas with good schools, don't have the same opportunities etc. (I believe, not 100%) Whilst UMAT is trying to test your inherent skills and not knowledge. Now whether UMAT actually does this is debatable, but I think that’s kind of the approach they were trying to take. They are essentially saying, if you can get 95 ATAR we believe you have the capabilities to complete the course, and then everyone’s on a level playing field with UMAT. (I think, this is my interpretation, may be entirely wrong).