And the cop will say "I don't believe you you terrorist" and lock you up until you say something else. This has happened time and time again, including in the latest Hong Kong protests, on American border interrogations and it will happen in these US protests as well.

Once you're on the list of suspects from someone elses Signal chat, you're not going to persuade a suspicious official by bullshitting.

Do you have a source for the claim that this has happened at protests in Hong Kong? I haven't heard of anyone being arrested here on the basis that they had Signal installed.

They got arrested by association. Signal chat group is such an association, just like other chat groups are. Except that Signal guarantees to give out your phone number (and by extension location and personal address) to every single person in a chat group.

There have been lynchings in India based on this kind of data leaked by WhatsApp which resulted in them finally allowing joining groups anonymously.

Do you have a source for this?

I mean, I don't get why it has to get any more complicated than "I have friends that use it". That's the main reason for having any messaging app.

How about "I searched for the term "private messaging" in Google Play Store database and Signal was the top result."

https://play.google.com/store/search?q=private+messaging

Rubbing ones hands together to stave off the chilling effect.

no one would believe you...

How does that matter? You have the right to install any apps you want, and wacky questions deserve wacky answers.

How does that matter? Perhaps due to the potential scenario in question being interrogation by law enforcement that doesn't have your best interests at heart, not "who has the better witty retort to score points online?".