Besides the positive stories from Iraq, I bet that NBC dumped Arnot because last April 4 (2003) he reported that the Euphrates River had been poisoned (disposal of WMD?). His story was attributed to MSNBC and picked up all over the world for one day. After that, the story disappeared into the black hole of elite media news coverage.
Here are the FR links from the time:
MSNBC - Cyanide & Mustard Agents Found in Euphrates River
EUPHRATES 'POISONED'
-PJ