I wouldn't necessarily assume it was the authorities who chose to make this public. Clearly, these coins are in the public interest, and anyone could have set up to be automatically notified once any of them moved ;then subsequently asked the authorities about it - forcing their hand. The truth is we have no idea how good (bad) this pot grower's opsec actually was. Maybe they just happened to 'find' the key(s). Maybe his keys were also in an encrypted file with a weak, breakable password. Maybe he used weak entropy for key generation; and they finally managed to brute-force one of them. Or, maybe the authorities have secretly discovered the secret to quantum computing 🤣