Please correct me if I'm wrong but I don't think that's true. Just because it's open source doesn't mean it's free, it just means that technical users could, if wanted, compile it from source. But, especially with iOS apps, this is not even true since you do need to have a developer license and a Mac to be able to compile and run it on an actual iPhone.
So in reality, while this is open source, only developers who pay Apple, are able to install this application, even if it's open source.