Are you joking? This is the exact opposite of plausible deniability. This feature requires premeditated user action to hide evidence in an attempt to mislead law enforcement. It is illegal.
What happens when it becomes popular and police departments catch on? “plausible deniability” escalation is a two way street as others in this thread attest.
Then anybody trying to stop them from continuing this will be demonized for "trying to take away law enforcements tools needed to do their job properly" and say that this person supports terrorism and all the usual tricks to manipulate public perception.