Step 11 really needs a better description. I started undoing the tape that holds the case above the optical drive slot to the metal before I read the comments and realized what I needed to do. Once you start to pull the top case up from the front, you'll reveal enough of an opening to get a spudger all the way under the metal portion of the top case next to the first snap. Once you have the spudger in, it's easy to release the snap without worrying about bending the whole topcase. Just repeat for the remaining three snaps. Once I got this technique down, it really didn't feel like I was doing anything that might damage the case.
By the way... don't worry if you undo the tape. It will go right back together with a little pressure. I didn't even need to go out and buy some adhesive to fix it.