Regardless of the validity of the terrorism charge, it seems pretty reasonable to call what he did destruction of evidence.

Now, if he had taped "pass:1234" on to the inside of his phone case, and the CBP official had typed that in I'd argue it wasn't his action. But the act of giving false information that led to the auto-destruct is 100% equivalent to him typing it in himself.

The lesson imo, is to have something similar to trucrypt / veracrypt, in which multiple passcodes can unlock different sections of an encrypted drive (and the empty space is encrypted as well with a random key). That way, you have much more plausible deniability ("I gave you the key"), and it's not actively destroying evidence.