The problem I have with this explanation is that the way the kill switch was implemented is way more complex and convoluted than it needs to be. It sounds like what they had done was fully implemented the feature but not the rest of the service they were going to provide, but they implemented this feature in such a weird way. The phone home code sets a global variable which is then read by another completely unrelated thread which sets another global variable which is what then actually does the mining shutdown part when the machine requests work. That is just way more complicated than it needs to be. The full feature could have just been implemented in the same function that they wrote for the phoning home, but instead it sets global variables used by other functions and threads.