All the same China could opt for a compromise position, something like Chinese Bitcoin; a digital exchange currency backed by gold.
What is to stop them from abandoning the gold standard at a later point in time, like the US did?
They have already abandoned the gold standard when US got off gold standard all money was truly Fiat, free floating money with no intrinsic value other than the value of the paper it is composed of. Maybe China wants to become the world reserve currency knocking the US off this position we have enjoyed for so many years. I guess they want gold so they can at least be part of a group of currencies that will compose the backing of a world currency. No gold no vote.
I don't think they are going to establish a new world reserve currency. They are always quite happy with being only the second best. My guess is that they hoard gold just in case dollar should fall. This way their gold reserves will serve a hedge against such a possibility. No matter what currency becomes a new dollar (or even if there is none), they would always have something to exchange for it, or just directly use their gold as money.