Why Grassley chooses to provide her with a closed door alternative is beyond my understanding. But then, I'm not a spineless jellyfish. The only thing I can think of is that Grassley has to appease the most stupid Republican in the Senate, Susan Collins.
It's simply a political calculation to be accomodating to the woman. It doesn't matter what she says at this point. It will be calm, polished, and slick like 1991. She has perfected her story since 2012 using multiple counseling sessions. The words coming out of her mouth will look convincing to many. Better to have minimal exposure or none at all.