Zhang Xuefeng's Professional Recommendations:

From recommending civil engineering to dissing civil engineering,
then dissing liberal arts and recommending computer science,
to finally pushing civil service exams and public sector jobs—what's the underlying logic?

I've also watched clips from Zhang Xuefeng's livestreams before.
The underlying principle seems to be: "Don't listen to experts, listen to the state."

At each stage, Zhang Xuefeng's recommendations stem from his personal perspective aligned with national development plans to suggest majors.
This is no different from KOLs in the industry—whatever is trending gets written about and promoted. There's no fundamental difference.