I think that's taking it a bit too far. It is a potent androgen, but it is not the MOST potent androgen. I believe Anadrol 50 is still the king there.
Also, Tren only cycles are not very good for building muscle due to a variety of factors. Tren always seems to work best stacked with another drug. If mass it the goal, then using a potent androgen such as Test, D-bol, or Anadrol 50 works well, which explains why he experienced good gains.
Tren is primarly used in cutting cycles rather than mass cycles due to its superior properties for cutting.