Rights are a human invention.
I reject that notion. As was written 250 years ago:
"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. ..."
Unalienable rights belong to you by nature and cannot be sold, traded, or removed by any government.
That doesn't change the result here, but I think it's important to start from that position so we can, as you noted, "fight sufficiently to protect that idea". It can mean the difference between arguing about how a law is implemented versus arguing that the law is wrong, unjust, or invalid. That CBP can violate ones rights with impunity does not nullify those rights - they're just getting away with the violation. It can even be legislated and adjudicated in the governments favor, but those rights remain.
TBH, if GrapheneOS was in more widespread use, or if similar features were available on the other major platforms, then we could ALL setup and use duress codes in such cases. That would put a kibosh on them trusting peoples PINs and would exercise our rights.
I'm a bit curious how such a wipe differs from doing a preemptive wipe? Cause that's the advice I've heard EFF and such use for ages now - don't bring your actual phone, or wipe it before getting on the plane. I do understand that they had the phone in their possession, and border stuff means that could be considered evidence, and lying to law enforcement can be illegal, and this could be construed as destroying evidence... but the end result is identical. How long before they deny entry if you don't have phone with lots of history and social and such?