Their way around it is they say that the border crossing technically isn't 100% normal US territory and therefore some constitutional rights are suspended under the concept of "sovereign self-protection". You could then say any law in the US could be used to justify this concept, in fact it was used to forcibly intern thousands of Japanese and Japanese-Americans during ww2.

He was targeted for purely political reasons, the cop-city environmental protest in Atlanta GA, and I'm wondering why the border officials were even aware of them. Is there some sort of "we don't like what you think" list run by the gov?

His device was threatened with seizure even though he posed no threat, no visible threat or spoken one, no suspicion of a crime, and they had no idea what the contents were. His 5th Amendment rights were violated by the threat to seize it. They want to establish a precedent, that the very existence of a possibility of criminal contents, regardless of any reason to suspect any, is sufficient for search and seizure. Based on this a little kid deleting the contents of their ipad would be a crime.