Article states that “…. the message triggered alarm bells after being picked up via Gatwick's Wi-Fi network”.
This doesn’t make sense. Snapchat doesn’t use E2E encryption for chats, but they do use TLS. So unless they got him to install a root CA onto his device (which I also don’t think would make a difference due to SSL pinning) I don’t believe this to be true.
Feels to me like he was either already being monitored by UK security services via a compromised device / the cooperation of Snapchat, or someone reported him.
Also, was this a bad idea and a tasteless joke, yes. But if all he did was send a bad joke to a private group of friends, I feel this is an overreaction and proof as to why we need E2E encryption widely.
What is highly likely is that Western agencies are scanning messages for threatening statements and using algorithms to rank the likelihood of something being said as a joke or as a true sentiment.
There may be things we don't know. Perhaps there were legitimate threats to planes out of that airport and this was a terrible coincidence.
In any case the fact remains that the government would not have been able to see his message and would not have put him through this ordeal if he and his friends were using end to end encryption.
Computing power and algorithms are getting effective enough to scan the world's data in real time. The only way to protect yourself is to stay invisible.
In this case, the fine should be directed at the agent who made this call.