The regulation gives manufacturers quite a lot of leeway on how easy it is to replace the battery. You could make the display a battery, just make sure users can replace the display with pull tabs, a set of precision screwdrivers and whatever other commercially available tools you want. And from just skimming the regulation, I don't see how devices would be forced to have a battery. It talks about devices with batteries, and batteries in mobile phones, but if your device doesn't have a battery then this regulation simply doesn't apply.