If you take these comments at face value, then you’re probably right, they will help support the dollar. However, given how much talk has happened lately regarding dropping the dollar as a reserve currency you have to wonder how reliable these comments are.
In general I think that China, India, Russia, Brazil, and the other developing countries would like to see an orderly move away from the dollar as the reserve currency. But it’s doubtful that such a move could be orderly. So, that leaves us with either, dollar remains the reserve currency, or a sudden move that either causes a crisis, or is caused by a crisis.
I’ve got no real insight into which path this will take. But I suspect that whatever is going to happen, will happen regardless of the speeches given by various officials, either Chinese or US.