Well, you have to think about what it means for the Judge to tell Valentine to "Be" (and I think we should avoid the qualifier "just").
He means that Valentine needs to just Be Valentine. This doesn't preclude the taking of specific actions, because Being Valentine means taking specific actions, like stopping while drinking a bottle of water to say "Bonjour" to a complete stranger, taking Rita to the veterinarian's, reaching out to the Judge, and helping an old woman put a bottle in a recycling bin.
What more can any of us do than "Be"? We can, perhaps, become a better Number_6, or a better Friday, etc., but we can only Be Number_6 or Friday, etc. It is beyond our capacity to do anything more.
The Judge's "Être" is a philosophical "Être," as in Sartre's L'Être et le néant (Being and Nothingness).