Yeah that’s not how CBP works especially for non citizens. I tell Americans this all the time and nobody believes it. Until it happens to them or someone they know.
You have zero rights. You can be detained without legal representation or cause for 72 hours thanks to the Patriot Act. Even as a citizen. Your electronics seized and spied on. All your social media, email, picture, everything read. It happens daily.
It happens more often to black and brown people and non citizens. But it shouldn’t happen at all.