Digital BW, The Print

I have someone claiming they can develop TMAX in RS developer and get a
density range of 4....yes FOUR!  I am very skeptical.  The most I've gotten
from T-MAX, in TMAX developer (which yields higher density than RS
typically) is a bit less than 3, and my typical Tri-X is around 2...and
Plus-X a bit more than 2...but FOUR!  Needless to say, I'm skeptical.

What's the poop?  Is this guy pulling my leg, or is his claim possibly
legit?

Austin