"Only a Minority" Inquiry

Hi LSAT Max! After reading the discussions, I understand that "only a minority" is treated as "a majority DON'T". However, my thought process while doing this question was to treat minority as "some". I was hoping that someone would kindly explain why "minority" should be translated to "majority not" and if there are other instances in the LSAT where this kind of transformation is needed for accurate diagramming. If someone could clarify my confusion and help me figure it out that would be great! Thank you in advance!