Stating what to me seems obvious:
According to previous court rulings in the US and even the complaint against Silk Road, owning and mining Bitcoin is legal in the USA.
Buying and selling illegal drugs online using fiat or bitcoin is not legal.
Operating a securities exchange that is unlicensed by the SEC seems to be a bit problematic, also.
On the otehr hand, there seems to be a network of OTC stocks that are traded. I am not a lawyer but it would seem that public companies need to comply with some government requirements to be offered to the public. Also, there are minor exchanges in the USA like
http://www.nsx.com/. Perhaps Active Mining could be listed on one of these minor exchanges. Of course, if it gets listed on one of those exchanges, Ken would have to comply to a whole new set of rules and Active Mining would then be traded in US dollars instead of bitcoin. On the other hand, it would allow for Active Mining to be traded somewhere legally.
The question I would like to have answered is, What is required of a company to have it publicly traded? Can a company be traded without an exchange? What is required for an exchange to meet SEC approval? The fact is, there are several small exchanges in the USA such as the one mentioned earlier.