How on earth would any test be anything more than a "socially constructed concept that ATTEMPTs [sic] [to be] a method of measuring intelligence". That just sounds like a definition to me, not an indictment. Do you have a better test?
No one claims the SAT, or any other test, is the final word. But at the same time pretty much everyone accepts that that "general intelligence" (or something like it) exists, and that tests are a reasonably good proxy for detecting it. To first approximation, students who do well on the SAT are successful in other ways associated with "intelligence".
And that -- the fact that the SAT correlates with something under study -- is all that is needed for good science. Even poor correlations can be enlightening if the data (and scientist) is good enough.