The difference is that this guy gave a code that wiped the device while it was under investigation. That's obstruction.

If he wiped his phone before crossing the border, he would have been fine.

If he refused to give his password to the phone, he would have been held up for a bit and then he would have to leave his phone, but he would be fine. American citizens cannot be denied entry into the US.

The difference is that the phone was wiped while it was under investigation because of an instruction he gave the CBP. That was ill-advised because that is clearly obstruction. He didn't understand the law and now he's probably going to pay for it.

And I say this as someone who had a very bad experience at the border. A CBP accused me of not being the same person on my Green Card and I had to wait 15 mins for that to clear up even though there was nothing to dispute here, it was me. The CBP are fascists and it doesn't matter who is president, this was during Obama's presidency.