Python is definitely major player in data processing (heck i'd even just be interested in how he's defining data science), but it's definitely not the only game in town by a long shot.
Summary: "Constantly switching languages is a chore, and while Python isn't the best at everything, it's the best at some things and good enough at almost everything else."
As a long-time Matlab user, I'm currently working on migrating my skills to Python simply because the small amount of functionality I may lose (decent IDE with integrated debugger and workspace viewer) I gain back with loads of other tools (like extensive out-of-box support for databases, way better memory management, and exciting developments for targeting GPUs and compute clusters).