If all crime is committed by South Asian women, you're right that it would be madness not to use that information to target crime-fighting measures such as, for example, only looking for suspects that are female and have a South Asian suspects.
Profiling, however, where you preventively search if not outright harass people, is something entirely different: if one in ten South Asian women engage in crime, every time you preventively search and harass one of them, you have a ninety percent chance of searching and harassing someone who is innocent.