But they might take you down to the police station and wait for your lawyer to show up. Do you see that as a successful outcome?
Second if you're being interrogated than you're suspected of something.
You're just plain wrong about that. They may think you're a witness or have information that they need.
But once they start asking about you that's when you lawyer up
But if you don't have any information, or if there's even the most remote possibility at all that you could somehow be implicated by the information you have (or by the fact that you have the information in the first place), then plainly, simply, and politely: "I have nothing to say" and "May I go now?".
I think this is the key difference of perspective between you and the people you're debating. But what's interesting is that you're arguing the tactical disadvantages of something you believe people have a civic duty not to do. Are you sure one opinion isn't influencing the other?