Update! It doesn't float... took about 30 pounds of force to get it off the bottom. Pretty much exactly the weight of the aluminum in the keg.
[video=youtube;hPb0sHp6wTM]https://www.youtube.com/watch?v=hPb0sHp6wTM&feature=youtu.be[/video]
[video=youtube;hPb0sHp6wTM]https://www.youtube.com/watch?v=hPb0sHp6wTM&feature=youtu.be[/video]