Hello again!
The question stats that Yang Ming/Shao Yao are ‘the two superficial meridians’ and not “the most superficial (that would be Tai Yang”). For Bell’s Palsy, the Wind enters the superficial meridians according to 6 stages with Yang Ming/Shao Yang being more prevalent on the face (think of how much the ST/LI/GB especially cover parts of the face). So, Tai Yang, Yang Ming, Shao Yang are considered the 3 superficial meridians in 6 Stages since they are all Yang stages (with Shao Yang half exterior and half interior).
Does this help?