Yes, agreed it’s not standard usage and that is why I initially resisted the idea when @AustenNut first suggested them a couple of years ago. But I’ve come around 
and think it doesn’t matter if they are named differently because all we really need is that a student has a balanced list with an appropriate number of schools in each category.
In other words, it doesn’t matter if the >80% acceptance school is called a “safety” at their HS and “extremely likely” out here, as long as the student has one affordable school in that bucket. But IMO the latter nomenclature will better help a student categorize their list.