Rhys Morgan, a young man with a serious illness who decided to expose some of the cranks and con-artists peddling harmful alternative "cures" for his condition, is beginning to experience the early stages of an organised stalking campaign.
This may get worse, but he may also find that many of the threats are empty ones. If someone is really going to sue, they get a properly registered solicitor to send a letter. Threatening e-mails have no legal force whatever, and the person sending them is almost certainly breaking the law and/or professional codes of conduct.
The way to tackle this kind of thing, is to keep striking at the head of the snake (or the snake-oil salesman) and not to allow skanks hired by the snake oil salesman to divert attention from the con.
The people doing this are in the United States, they are almost certainly breaking Federal Laws and are exposing themselves to massive civil liabilities from people they have sold harmful substances to on the basis of false promises. They have a great deal more to lose from a court battle that Rhys Morgan has, so what they are doing is lay down a barrage of threats of legal action, as well as threats of a more direct nature (sending him Google Earth images of his home, for example) precisely in order to keep the matter out of court.
The stalker's next move will be to use a campaign of lies to induce individuals to initiate some kind of physical harassment against Rhys and his family. These lies may be completely unconnected to Rhys's campaign, and probably won't be based on even a grain of truth. At which point, he must contact the police, very firmly and preferably with a solicitor in tow, and make it plain that there is a criminal smear campaign against him, and that it is taking place in order to protect a large scale consumer fraud.
The ACPO advice, which leads many police forces into abject failure on stalking cases in particular, is effectively to blame the victim for provoking "anti-social behaviour" from conveniently unidentified local "kids". (The Data Protection act supposedly (but not actually) makes it illegal for the police to tell the victim who they think it might be!)
It is very important to squash this suggestion from the outset and every single time it is subsequently deployed, because a succession of police officers will be involved, and it only takes one of them to succeed in making this suggestion without challenge, for it to go on the file and become the official explanation for any crimes committed against Rhys and his family. The above advice may sound hostile to the police, but it's necessary to recognise that many of their guidelines are issued precisely in order to limit the number of cases they get involved with. They will help, providing that the victim can ensure the case is recorded and presented in a way that triggers investigation and solution, rather than pallative or evasive measures preferred by the more political levels of the criminal justice system.
If threatening e-mails originate from the USA, this is where to report them.