No it isn't. I never said anything about making hiding DNA illegal, just that it is impractical. If you want to map it onto cryptography, I'm making the rubber-hose cryptanalysis argument[1][2]. People are worried about some evil entity going through proper channels for their evilness when there are more blunt and direct ways to get what they want.

[1] - https://xkcd.com/538/

[2] - https://en.wikipedia.org/wiki/Rubber-hose_cryptanalysis