Why would you need your sponsor to submit falsified visa support letters to Foreign Office? This is what people are complaining about, it's not just ML, where do you think he got the info from ?
Besides, if they are innocent then they have nothing to worry about.! Both GEO and the visitors knew what they were playing at.
Just another example of how easy it is for innocent people to get caught in the crossfire:
BBC Accused of Endangering Students in North Korea Trip | TIME.com
Easier to get an "Artist visa" compared to "work visa"? Since they were let go, am sure your government was satisfied with whatever explanation GEO gave them.