This is not true.
The 2% rate of inflation has nothing to do with gold. It is purely a construction by a New Zealand finance minister who recognized that cost of living increased ~1.7% a year. That finance minister then became a board member of the central bank of NZ and the central bank set the first inflation target of 2%, which caught on around the globe as a standard inflationary target.
This all happened in the late 80s early 90s.