If the seat is meant to recline, why not use it to make your journey more comfortable? I don't get why people shouldn't be able to do that. The person behind them can recline their seat too if they wish. On most long haul flights that I have been on, the cabin crew ask people to bring their seats back up when the meal is being served. But if someone wants to sleep, I don't know how they can be forced to. On a 20 hour journey, there is no way that everyone is going to want to sleep/eat at the same time, so I guess there is always going to be fodder for conflict.
I'd tend to be on the side of the sleeper in that story. I've been able to eat my meal perfectly ok when the person in front of me reclined in their seat. 'Twas a bit more cramped than I would like, but it was totally doable. On a 20 hour flight, there would be several times that meals and drinks are served. I don't think its fair that some one who is trying to sleep should be woken up and made bring their seat back up every time the food or beverage cart shows up.