It's a good idea, but difficult to implement I imagine. It should be possible to select text while also making it impossible to copy on mobile platforms. They could make it an app feature, but not available on the site.
Could be a bit of a nightmare too, with hundreds of people reporting the same typos. The prepubs don't get updated, after all. So the current system is fine with that in mind.
Therefore, the best option for now would be to link to corrections topics from within the reader.