Well you want the real reason Opera was rejected. It is all about money. On Safari apple gets a slight cut for all the ad money made though good searches you do though the phone. Take for example firefox. That night little default Googe search in the top netted Mozilla 72 million off google searches alone a few years ago. Back when firefox when firefox was just in the 1.0 stage.
That is the real reason. It is not about consumers but about the money. Apple is what I call a chicken company and has little faith in its own products standing up in a head to head fight with the competition.
Are you certain this is the case? You're saying that Google pays them for everytime someone searches in the iPhones Safari browser? Or is it just because they have it as their default search engine? If the latter is the case then it wouldn't really matter that there is a different browser either.
Also, could you provide a source for this? This is the first I'm hearing, I'd like to read more.