Do you think that a person wearing a police uniform (that every person has an obligation to obey so long as they make a lawful order), can also, in the performance on that same duty, lie directly to a member of the public?
As the law stands, they are allowed to lie as much as they want when in uniform, in public, and anything you say or do in response can be held against you in court. The proposed Virginia law forbids that in the case of children who are interrogated.