In this instance i have to think it is a legal matter.
The only thing that matters is what Russert says on the witness stand in the trial of Libby.
It is also at this time strategic to NOT let the the opposition know anything on what cards you hold or will play at the trial.
The fact there now will be a trial, a key element of the indictment was Russert's testimony, any discussion before hand will accomplish nothing, and could assist the opposition.
This is a major trial coming up, that is when the story should be unfolded, not before.
This trial is the nitty-gritty time, all before it will be meaningless.
Russert caved? Why??