While police are allowed to lie, are they allowed to lie to you with regards to what rights you may or may not have? Naively, it would seem so but I'm not aware of any language explicitly allowing deceit on the part of police.
https://www.nytimes.com/2011/08/21/opinion/sunday/sex-offend...
If the contents of the disk are a foregone conclusion (and assuming the article’s framing of the “foregone conclusion” idea is correct, and I’m not even close to being a lawyer so I have no idea) then it seems like a slam dunk that they would be able to compel him to produce the incriminating contents of the disk - but not the password that unlocks the entire disk, presumably including things that don’t have that “foregone conclusion” status. Or they could likely just use his statement as evidence of the content of the disk. Either of those would almost certainly get the conviction they want with far less drama.
But I think criminals being interrogated aren’t really of sound mind.
I think the point (which bears repeating) is that suspects are not criminals until proven so in a court, and it's important to be careful in our language, especially in our modern times where the court of public opinion operates swiftly and without due process.
It also would've been better had he not been a pedophile and yet... we are here.