Just make sure that NO COPY of the GM posted on the torrent is present on your computer. When I installed mine just to test if I really wanted to buy it later on, I partitioned my disk and installed into that partition. Deleted the partition after testing, thinking that will be it. NOTHING. Same Problem. Same Email account showing up.
I later found out I had a copy of the GM on an external drive. Deleted from the external drive and emptied the trash.
Opened Mac Store and VOILA! Instead of showing the DOWNLOAD this time was showing FREE UPDATE. Pressed... Downloading now. SLOOOOOOOW as hell even having a 50MB/S download stream but... Downloading..
Hope it helps. Search for ANY COPY you still have on ANY PLACE or HD on your computer.
Well I'm beyond that now, but it'll be interesting to see if others get a similar result. I had downloaded to my Downloads folder and then dragged the installer to my desktop. I had tried moving both to a temp folder under my home dir and even later to the trash, but still couldn't get it working. As noted above, emptying my trash didn't work for me.