In addition to being untested, the above uses an extremely poor way to
get the size of appliance.raw.
Anyway, either that section of the wiki page needs to be deleted, or
it needs to be replaced with instructions that actually work. Note
that you have those instructions in at least 2 places on that wiki
page, maybe more.
fyi: I also just edited the dd command for writing to the thumb. It
now has a "conv=fdatasync" arg at the end. That's important for
thumbs that don't have lights.