Comment by ruilov

from the opinion: "[Tiktok] further argue that the Act is underinclusive as to the Government’s data protection concern, raising doubts as to whether the Government is actually pursuing that interest"

ie what you're saying...the Court replies:

"the Government need not address all aspects of a problem in one fell swoop...Furthermore, as we have already concluded, the Government had good reason to single out TikTok for special treatment"

Congress can solve one problem without needing to solve all problems.