The article describes a bad programmer as one whose programs “die young”. I would guess that Knuth is saying is that the longest one of his programs lived (was

The article describes a bad programmer as one whose programs “die young”. I would guess that Knuth is saying is that the longest one of his programs lived (was used?) for 12 years? If that is what he meant, I presume this remark was written well in the past, as TeX has lasted way more than 12 years.