Even if the prompt was vague like "what's the pin for the phone", you'd be hard pressed to convince a judge that a duress pin (to wipe the phone) is a reasonable person[1] interpretation.
The fact that the feds are using an obscure law to argue that he destroyed property to prevent it from being seized shows that they're reaching here.
This doesn't pass the sniff test. Consider the following:
Cops: "where were you on the night of the murder?"
Suspect: "at work"
Cops: "You're lying, we found surveillance footage of you near your girlfriend's apartment"
Suspect: "ah-ha, what I actually meant by 'at work', was that I was mentally at work!"
Of course, there's some grey area where the suspect gives cagey or vague answers, but in this case by giving a duress pin, it's pretty obvious the intention was to deceive the CBP officer.