But rooting the phone by default doesn't touch the radio files. It grants the user access to the system (the root). And installing CFW doesn't necessarily muck about with the phones radio files (after all, they should be fine in the first place), it installs other items.
Just rooting shoudlnt touch the radio files. All rooting does is unlock the phone and allows you to do what you want basically. Apply custom roms, themes, remove bloat...that kind of thing.
NOw if he is switching kernals and trying to go from 1.5 to 2.1 or 2.2, then he may have to flash a new radio as well. Again, not sure on the PULSE phones so this will need to be researched.