John Glenn was grounded after his first space flight because the administration did not want to risk killing their space hero. It was not his choice, for his heroism he was made the victim of administrative cowardice.
I was surprised they didn't know that. If you had asked me where I learned that John Glenn was grounded as a political decision, I might as well have said the SGU, for all the astronomy related material they have.
Edit: It might be speculation that it was a political decision, since there doesn't seem to be an official statement about it.
Edit2: And there's the ad;
Steve: "Well everyone, let's take a quick break from our show to talk about our sponsor this week, [redacted]"
Cara: "Yeah you know, we talk about it a lot, and that's because we love it so much
That's where it all falls apart. If anyone was looking for my input on how skeptics could improve doing ads.