Should employers be allowed by law to add a gender preference searching for an employee for any job?

What if an employer is looking for a female model? Of course they are going to prefer women as an employee. An employer is a person, and in our society, has a constitutional right to be as discriminatory as they want to be unless they are a public institution. If we feel that the discrimination is unjust (i.e., preferring one gender over the other in a job where that has no bearing), then it is the duty of us, the people, to refuse to support that business until they change their ways. Now, in certain cases, where there is a history of unjust, institutional discrimination, the intervention of the government in private affairs can be justified (i.e. the civil rights movement of the 60s). I think that our society (in the US) is able to overcome this issue without the government interfering, although that is a more subjective argument, which is the subject of debate today.