Most lenders or AMCs do not formally remove an appraiser, especially for coming in "low," because that would mean documenting it . They simply make an internal decision and stop sending that appraiser orders ( or send them two token orders a year so that they technically remain active )
I doubt there ever was a "hearing" scheduled, and perhaps the OP was confused about it. If anyone at the lender or AMC organized a hearing, it would be the first one I ever heard of.
If there is an error or a quality issue, sometimes a client ( or Fannie or freddie ) might send a warning letter or put the appraiser on a probationary status; they have to take a class or such.