There is no system in the world which is 100% safe and secure and completely impervious to all attacks. However, this article makes it sound like stealing data from an air gapped machine is almost trivial, which it obviously is not.
it's one thing to want to stay protected from a thief who targets you and wants to steal from you. It's a whole other level if you get on the radar of a serious government agency who decides to take you down (darknet markets, Silk Road, etc.). Your primary concern should be to to remain protected from the first type of adversary. Your secondary concern should be not to do illegal things that would result in you becoming a target for the latter. Because if you do, you are gonna have more important things to worry about than how safe your bitcoin wallet is. This is not a response to your personally, just some of my thoughts. No one is untouchable.