> Why do you think that doesn't apply to the situation he was in? He was suddenly arrested (detained anyway, so his freedom was taken from him) and he, as an activist, had contacts on his phone of other activists who would have been criminally charged, killed, or disappeared.

Because he knew in advance that he would be crossing the border. If your threat model includes ensuring that US border control does not view the contents of your phone, and you're returning to the US after an international flight, then you need to take appropriate precautions (i.e. wiping your phone beforehand rather than after they've taken it). It's not like the police suddenly raided his house in the middle of the night. Obviously I feel bad for the guy, but if he had acted differently he would not have been criminally charged.