I think the Omnia handles the carrier line differently than other PPC's. I can remember with the 700wx struggling to remove that pesky line doing nothing but advertizing VZW (like it isn't already emblazoned on the body of the device) until I found HideLogo, but on the Omnia it is handles as a Today Plug-in AKA optional. I think that blocks the carrier name from being picked up by other apps the way they usually find it. SPB MobileShell is blank on top as well as a few other apps I use.
If you really want it to say something Personalizer still works (found in the software forum). I use it just for aesthetics!!
edit: Just for kicks...here is the thread to download and read about Personalizer:
http://forum.ppcgeeks.com/showthread.php?t=21538