The only thing they've provided are the parts that they used that where GPL from start, and they have done so from the start:

"The Pronto products contain software provided under a variety of licenses. Some components are "free" or "open source" software, while other components are proprietary.

Pronto products may contain software that is based in part on the work of the Independent JPEG Group. Pronto products may contain software of which portions are copyright 2010 The FreeType Project (www.freetype.org) Pronto products may also contain libcurl, for which copyright and permission notice apply."

These are:

busybox-maestro
glibc-maestro.tar
libcurl-maestro
libfreetype-maestro
libjpeg-maestro
libjs-maestro
libpng-maestro
libsdl-maestro
libsdl_image-maestro
libsdl_ttf-maestro
libuclibc-maestro
linux-maestro
lrzsz-maestro
mtd-utils
wireless_tools-maestro
wpa_supplicant-maestro
zlib-maestro

While it would be possible to use freescale drivers and a ARM version of linux, how would we flash it on the Pronto? How would we get the touchscreen running? And there is probably more that would be really hard to do that I'm overlooking.