I do agree that this wouldn't work out for the average criminal trying to move Bitcoin back to fiat.
I don't want to give anyone any ideas of but they would either need to force someone under duress to cash in the Bitcoin on their behalf or they would have to convert it for ZCash or Monero and then spit it up and convert it back into BTC making a bit of a loss but they could sort of "Clear the trail" if you will and get their fiat
They could also send the Bitcoin to dark web suppliers and purchase things like drugs in exchange.
There are potential loopholes we should be aware of when looking to improve the cryptocurrency protocal. I'd like to see things like a smart contract ID verification attached on a side chain. For example what Civic is doing and then using NULS as a module to add onto a blockchain or as a secondary segwit. That way we can make transactions identifiable for public use between peers.
This is a horrible situation and I really feel for the family and the boy, this is not why I want South Africa making cryptocurrency headlines.