Hmm... Give false positive enabling software to law enforcement that will be disseminated to "Concerned Parents", then spend time investigating "Crimes against children."
What is the rate of which this software has been used to investigate crimes?
Who designed and programmed this software?
Police are not mandated to prevent crimes, and have no external incentives to do so (I state external because some officers want to reduce crime due to morals/ethical beliefs). In fact, in can be argued by looking at civil forfeiture laws and federal programs paying officers directly for certain arrests, that preventing crime is actually against their best interests both organizationally and individually.
However, handing out a tool that always indicates suspicious activity and allows them to invade privacy.. well, that fits in exactly with the behavior that laws and rules surrounding them have encouraged.
What's unclear is, do the cops get access to the keylogged information? Then the metaphor gets silly. It's like... firefighters giving you a smoke detector so they can spy on you in case you're setting fires, which also happens to sometimes cause fires independently.
Zero. It's not a forensic tool; any "evidence" collected with it would be inadmissable in court. (And, as the EFF notes, its search functions are pretty much useless anyway - most major OSes have considerably better search built in.)