[0] https://www.fincen.gov/sites/default/files/news_release/2014...
> The first ruling states that, to the extent a user creates or “mines” a > convertible virtual currency solely for a user’s own purposes, the user > is not a money transmitter under the BSA.
That seems to leave rather a lot of open space IMO. For example, does a POS validator create convertible virtual currency? Clearly. But is it solely for their own purposes? Do they become a money transmitter as soon as they sell their crypto? Also, only part of miner income is the block reward; there are transaction fees as well. Is a miner allowed to accept fees from sanctioned individuals for providing payment validation services?
2014 was forever ago in crypto terms of course, so I can imagine that the viewpoints of regulators have evolved together with the technology.
Of course regulations can change, but in this case it seems unlikely unless the intention is to effectively "ban" cryptocurrency.
I don't think "but I didn't know that it was a NK wallet!" is going to hold up in court either. There are laws regulating the minimum Know-Your-Customer a money transmitting company needs to perform and when the regulators come knocking you need to be able to show your procedures for that and how they lead to compliance with the law.
The real question is whether courts will rule that POS validators are "money transmitters" in a legal sense. To me it's kinda obvious that they are, since without the action of the validators no money would get transmitted. No doubt there will be much water under the bridge before that gets settled though.