I don’t think that the email was intended to cover up instructions that Obama issued at the meeting. I think it was to cover up stuff that had already been done.
That’s certainly possible, too. But the choice of that specific meeting for the CYA operation indicates that something happened in that room on that day that the people in attendance want to keep under wraps.
I think it’s so Susan Rice could say in the future: “But POTUS Obama told me everything was by the book”!