Then get them wet and use an iron, set for the coolest setting, and iron
them flat!

I use my dry-mount press to flatten prints even if I don't actually mount
them to anything

  The journal article applies to uncoated paper.
Photographic prints are a complex structure. "Fiber" base
prints are coated on special paper which has a sizing of
hard gelatin. This sizing may consist of several layers of
hard gelatin at one layer of which contains a reflective
substance, in fiber paper usually Barium Sulfate (Baryta).
The gelatin emulsion is coated on top of this substrate.
Most papers also have a coating of hard gelatin over the
emulsion to resist abrasion. The reason that paper curls is
that the emulsion and substrates shrink at a different rate
than the paper backing. The shrinkage depends on the
moisture content of the gelatin. When the paper is subjected
to high heat during drying so much moisture is driven out
that the gelatin becomes very shrunken causing strong
curling. Many commercially made prints were dryed on heated
drum dryers, often at high heat to increase production rate.
In addition some prints were subjected to mechanical
deformation in so called print straightening machines. These
machines draw the print over a straight edge to stretch the
gelatin layers mechanically. After many years of storage,
especially at low humidity, the gelatin layers may become
very brittle. Adding moisture may at least partially repair
this but it also may cause some damaged gelatin to come off
the paper base.
  I don't see any advantage to refixing. Any residual
silver in the prints will long ago have changed to a form
which is no longer made soluble by fixing. If the prints do
not show staining there is no residual silver in them
anyway. The hardener in the fixing bath is also probably not
desirable as strongly curled prints indicate the gelatin is
already badly shrunken and hardening it will just make it
more resistant to swelling again.
 Seriously damaged prints really require expert attention.
There are conservators who specialize in this area.
 If rewetting is tried the prints should be dried slowly
and in a condition where the support dries faster than the
emulsion to minimise the differential shrinkage. This is
generally good practice for fiber prints.
 Note that flattening prints in a dry mount press also
requires differential drying. Prints flattened this way
should be placed in the press with the emulsion side against
a sheet of release paper. This effectively shrinks the
support more than the emulsion, which is what is wanted.
  The use of humectants, like Glycerol, may reduce the
shrinkage of the emulsion but is not recommended for
archival prints because the contained moisture tends to
encourage the growth of mold.

Wuss.