Are you sure about this? I'm running 2.1 on my Motorola Droid and to mute a call or turn speakerphone on just requires a simple button push. I don't have any issues with the proximity sensor on my droid but my gf just bought the moment and is having this issue. It would be great if 2.1 on the moment had the slide feature that you mention, but I don't see why it would be any different than 2.1 on my droid.
Yes I'm sure. I just tested it just for you. The place where you can get your self in trouble is that the home key will take you to the home screen, and then your face can open some apps for you while your chatting away, but you have to slide for speaker and mute. I wish I could show you a screen shot. There is also a slide to answer, but the hard key still works which is kind of redundant.