The point being is that you shouldn't have to switch views or exit the app to remove the highlight. That's bad UI and usability.
I agree that they need to add it, but I am still fine with the workaround right now, because honestly I don't even care that the tweet remains highlighted anyway.
It's a very nice interface that has made me use Twitter 10x more than I have previously. Usually when I use Twitter all I do is read what is in my timeline and replies, then maybe post a tweet. With Twitter for iPad I find myself browsing other people's feeds, just randomly exploring Twitter and finding new people to follow. It's definitely the best Twitter app ever made because of that reason alone.