Was in a similar situation, though the score was a bit lop-sided. It was the game against the Bucs and the play happens ( for those who have NFL Rewind or recorded the game ) at about the 3: 40 mark in the 4th Qrtr. Rahim allows Vincent Jackson to get behind him and gets lucky by the tips of his fingers. John Lynch did the commentary and he called it 'risky business'. We all know what kind of a Safety Lynch was.
We don't know what was said to Moore after the Tampa game, but I cannot imagine Del Rio letting something like that slide. I am thinking that Rahim thought he could make another play like he had done against Tampa Bay