let's suppose that we have found that telling the terrorists bedtime stories is an effective interrogation tactic.

If the information gets out the enemy could be preped for that tactic and render it ineffective.

Is this likely, no but you said make sense of it.

The point being, if you are willing to concede there are interrogation techniques that are not torture, it would follow that those techniques might be best kept secret.

I am not arguing the legality but to conclude that the only information we might want to protect is that we torture detainees is also somewhat irrational.

We choose to expect the worst or the best based on perception.