Comment by curun1r

It seems pretty obvious. Piracy is a synonym for particular sort of theft, but one that paints a very vivid picture of the person doing it as an outcast and a danger. If they had, for example, used the term 'digital shoplifting', which in the case of P2P is pretty close to reality, people would have brought their preconceived notions about the term which many associate more with teenage stupidity rather than hardened criminality.

Other synonyms for theft (larceny, burglary, robbery, etc) are too tied to the physical world to work for their purposes. The goal was to frame the conversation away from more accurate words like copying or infringement since those have more ambiguous moral connotations. Looking at the thesaurus entry for theft, I struggle to find a better alternative to piracy if the goal is to shape the way people think about the issue in your favor.