"Sometimes people forget things" isn't evidence. It must be tied to these facts. Who exactly got on the stand to provide the foundation for excluded evidence?
He also disallowed some video footage of Tim Russert saying witnesses could not have their lawyer with them in the grand jury room, in contrast to his testimony that he didn't know that.
The judge had a very narrow view of relevance. If an appellate court takes a broader view there could be a reversal.