[droithomme]

What if they refused to let her in because she was black?

Here they are practically claiming she is a terrorist. The principle is the same.

By sending her out you validate their discrimination, which is based on falsehoods and lies.

[Confusion]

  What if [..]

We can all sketch awful situations in which the appropriate course of action is obvious. This is not one of those cases.

  By sending her out you validate their discrimination [..]

No, you acknowledge they have authority in the situation.