The 4g ipod touch was discontinued May 30, 2013. So, they've been selling it to customers as a new product on store shelves until less than two years go.
I think the ideal scenario would be to show the App Store description and screenshots from the last available version. This way, it would be the version last advertised on the App Store.
The reason for the block on just automatically downloading an old version is that it is not the version advertised on the App Store. Advertising a product with features you won't actually get is generally frowned on. The reason the hack works is that it tricks the App Store into thinking you must have 'bought' an earlier version of the software, so supplying a previous version is fine.
Bear in mind governments take advertising accuracy very seriously. You casualy talk about free apps, but there's no such thing on the App Store now because the EU doesn't consider apps provided at no initial cost, but which might be add supported or have in app purchases as being free.