I don't know enough about Android resolutions & densities to write with confidence about what they say in that story but scaling down without actually changing aspect ratio should yield excellent results. Does Nexus scale down from something created for different aspect ratios?
My suggestion is based on not making any change to aspect ratio (so there's not minor stretching in either width or height). Instead it is much like sizing a higher resolution photograph to a lower resolution frame (but maintaining aspect ratio). It will still look very sharp). It's also like watching 1080p on a screen with a resolution smaller than 1920 x 1080. It too will look very sharp. In both cases, the picture or moving picture is just smaller, which we should expect when using a "mini" instead of a "maxi".
A scenario where something could get lost would be one in which very fine detail is applied to the retina graphic. For example, if something used a 1-pixel thick line as a crucial part of the graphic, that line might get lost by the downscaling algorithm. But the whole concept of anything at 1-pixel is lost in the concept of "retina": we're not supposed to be able to discern individual pixels.
Take it for what it's worth: I'm guessing the Nexus issue is because they are not only scaling down from higher resolution graphics but actually also changing the aspect ratio (thus adding a little horizontal or vertical stretch). Such a move would also be noticeable if Apple did that too. But my suggestion is to only scale down from iPad retina graphics with no change to aspect ratio. Then, the developers could just code for iPad Maxi and it will "just work" on iPad Mini too. If iOS managed the downscaling, the developers wouldn't have to do anything to make a resolution less than iPad Maxi look good/great. I'm pretty sure this would work well, and seem to fit into an idea of a mini having a resolution somewhat less than a full-size iPad, keeping pricing & battery issues manageable, and not creating another resolution for developers to target.