It was a good counter-point at "No". But since you went on, I now know again.
But jokes aside, the quote is direct anti-symbolism to the "But I have nothing to hide" and found it pretty effective, even in its silly nature, when arguing with people who are too eager to give up all privacy.
I think your analogy makes the wrong point. There are many reasons you might have something to hide, and to start with the simplistic ones your friends are presenting, among them is:
1. You did something wrong.
2. Someone else wants to do something wrong to you.
The first is in your control. I think I've acted with sufficient integrity for my life that I have nothing to hide which might land me in trouble.
The second is out of your control. There are unreasonable people in this world. If you have a stalker, you don't want them to know where you are. If your spouse cheats on you and leaves you, you might have a custody battle on the line. If your government goes the way of Germany or Russia circa 1940, you might want to hide your ethnicity or political beliefs. A police officer is investigating a crime, when someone you didn't like was killed; you didn't do it, but time, place, and motive are all there. None of these are particularly likely, but they do come up.
I have one person in my life, and to protect myself from them, I have a limited online presence. I use fake names, and my LinkedIn stopped updating a few years back which limits career prospects, but it's a sacrifice worth making. I let out a lot of information before that, which was a mistake. I went through some legal disagreements at one point, where another party acted unethically and decided to extort me. These things aren't in your control.
When I was young, I had nothing to hide. When I was older, I learned information is power, and information asymmetry can help you or hurt you. With that wisdom, I now have a lot to hide, and I advise younger folks to be mindful of their privacy.
I intentionally listed a lot of different things in my post, with fault lying in different places or nowhere at all, to give an idea of the variety of reasons one might want to hide something.
But jokes aside, the quote is direct anti-symbolism to the "But I have nothing to hide" and found it pretty effective, even in its silly nature, when arguing with people who are too eager to give up all privacy.