Well, the 80% accuracy the author reaches isn't anywhere near what you need in production for text classification. Imagine classifying all of Twitter with that... I don't want to make this look bad - the author did a great job at this "introduction to text mining" article. But the results are a far cry form prediction ready, as I hope would be obvious: Anything but a tiny false positive rate will just produce infinite false alarms (or miss all relevant cases).