I don't see why not.
First you are resumed innocent at least by US Law. So to claim that you setup the dead-man switch specifically to destroy evidence is to assume a priori that you are guilty.
Second, there are completely legitimate reasons for the scheme presented. Such as preventing absolutely anyone else in the world, other than the police, from accessing the data without your knowledge or consent. The fact that it is so elaborate and/or effective (I can't comment on that last bit) is evidence of skill not guilt.
Assuming a defendant didn't do something stupid like admit their real fear was prosecution using evidence of a crimes stored on those very same drives, I'd have a hard time as a juror finding the defendant guilty of evidence tampering. I am under no obligation to admit anything about those drives, to include my knowledge that the clock is ticking. That is the heart of the self-incrimination argument against having to decrypt a hard drive.
Mind you my assertions above are not backed up by a law degree and in some ways are still tenuous given the current state of jurisprudence in the various US courts. Though iirc, the SCOTUS has weighed in with a narrow decision along those lines. But I might only be thinking of a circuit court decision.