Earlier quoted context omitted.
I don't think this is an important distinction. In both cases there mere existence of the technology helps both good and bad parties to achieve their aims, that is all that matters.
You should think about it from a legal perspective: if you use GPG, will the FBI show up at your house just because the local drug dealer also does even though they never send you a message? Now, suppose that there’s a transaction chain which involves you – say said local dealer buying from one of the few other people using it — and how you’d prove that you weren’t a knowing participant in some sort of laundering sch…
I think that the ZK (ZCash, AZTEC, etc) technology will solve this problem and we will be back to the case where the government wants to make the technology itself go away.