I think you misread my comment. The data was comparing T25 students to all college students. The “all college student” group, by definition, is composed of mostly average college students ( presumably, a bell curve). In that group, many study nursing, which is great. Many study other things too.
The T25 student body is dissimilar to the average student body of the overall group in key factors. Fewer in that group study nursing, likely as a result of some of those factors. For example, the T25 students are disproportionately from top 1% in wealth or even .1% wealthy families. They may be much less likely to be interested in nursing. It is not just the difference in academic scores between the groups, but that is a factor too.