is it possible to use grub in a commercial application

[jurassic pork]

hello,
grub is a gpl v2 software , as i understand (may be it is wrong) i can 
use it in a commercial application only if the application is 
distributed with all the sources and must become GPL.
The commercial application is for only one client ( not a public 
application).
i would like to use grub only  in a part of the application to build 
bootable usb with winpe to install wim customized windows 7 client  
image on different types of PC.
why i would like to use grub and not bootmgr to boot winpe ? because on 
one type of PC , bootmgr doesn't boot -- > error 0xc000000e   Boot\BCD 
read configuration error.
Seems to be an usb bios issue.
If i use grub to map a winpe iso file and load it, it is OK.
Grub would be used only for solve the usb bios issue.
With syslinux it is also OK but syslinux is also GPL.
Have you an another solution ? commercial or not ?
Sorry for my poor english