Oh yes, let's not punish anybody because there's no way to be 100% sure of their guilt.
"you would never need to evacuate new york city as a bomb of that size is not feasible."
Ever heard of nuclear weapons? They're feasible.
Your refusal to use "cruel techniques" to possibly save millions of lives reveals a great deal about the content of your character, or lack thereof. There is no logical reason to protect the "human rights" of one man and cast aside the lives of hundreds, thousands, or millions of others, especially civilian lives.