Rehearsing?

I read that Alberto Gonzales has gone into seclusion so he can rehearse for his upcoming testimony.
Huh?
If he's planning to tell the truth, what's to rehearse?
Imagine yourself, fucking up something at work. Your boss comes around to talk with you about it and you tell him or her you need to go into seclusion for a few weeks to rehearse your answers.
What do you think your boss would say or do?
Should our country's leaders, like the Attorney General, be held to more lenient standards than some Dilbert in a cubicle somewhere?
The questions for Alberto Gonzales are very simple. Did you have anything to do with the politically motivated firings of federal attorneys or not? If so, why did you say you didn't?
If Gonzales wants to rehearse something, he should rehearse his answers for his next job interview. That's something he'll need to do soon, anyway.