I don't think too many pilots will commit this intentional act. Of course nor do they have to. It is far easier and 'passive' to simply leave the batteries on for 30 minutes after landing thereby (in most cases) overwriting all except the area mic's.
And here in this very thread we have the rumblings of the death of safety when outsiders move in and examine data for legal means in few cases. While on the other hand we have a promotion of actions from within the industry ready to decrease safety by globally wide actions against the use of these recorders.
In the end, should the investigation discover evidence that these recorders have been purposedly defeated you can bet that it will be front page news in the public press.
Is this really the way you want it to look?