This analogy is on par with, "if we can't trust them to wear approved patches, how an we trust them in combat?!"
In the absense of a law passed ordering police to torture, maim, rape, or execute prisoners I don't expect them to be constitutional scholars. We have courts for this.
Its the same reason I don't condemn college admissions officials for executing affirmative action for 60+ years. It was found to be unconstitutional, but I don't hold admissions officials personally responsible for following the law.