If you think Maggie is being bold there, just wait until you see what the rest of the scene is like!
Actually, I think it's amazing that Roger doesn't fire her. Though perhaps he couldn't because, even though it's not spelled out in the script, perhaps Sam Hall and Gordon Russell were operating under the premise that, as with the daytime show, Liz had hired Maggie, so she was the only one to fire her. Plus, as we'll see later on in Scenes 68 through 68C, the script wants Maggie to make her own decision to leave...