This is not even about deniable encryption (which is apparently a part of the threat model?): this is a nightstick to beat anybody who's inconvenient in any minor way. "Prove to me that your song collection contains no secret message, else you're guilty." There's no way to do that! For anything I could come up with, the universal response "well maybe it's hidden even better" holds.

In other words, introducing "guilty until proven otherwise" introduces witch-trials pretty much by definition: if she floats, she's a witch (so far, so good; yay it works); if she drowns (or dies in notprisonnosirnotatall after years of not confessing nonexistent secrets), she was innocent. Of course, there is absolutely no way this might be abused, and certainly not for personal vengeance.

Welcome to Salem, MA.