This complaint is addressed in footnote 10 of the article.
It would be great to design a test that's less gameable than the current version, and we should certainly try to do that, but the current version is already less gameable than basically anything else colleges consider for admission.
Whereas "holistic" admissions processes are probably the _most_ gameable option out there. If you were designing a process specifically to be able to game it (for example to keep out the Jews) then turning down the transparency would be the way to go.
It would be great to design a test that's less gameable than the current version, and we should certainly try to do that, but the current version is already less gameable than basically anything else colleges consider for admission.