Decompiling code is a reverse engineering method that provides access to the non-copyrightable elements of the code.

Yes. It also provides access to the copyrightable elements of the code. In this respect the decompiled code is identical to the object code, which is also made up of a mixture of copyrightable and non-copyrightable elements. Combining copyrightable and non-copyrightable elements into one thing gives you a work that copyright can be asserted over. The argument in the case you cited is that the defendant extracted the non-copyrightable elements and built their own work based on those. That's not what's happening in the case under discussion here, which is derived from the copyrightable elements as well.