China inflated the value of its currency, they didn't inflate it by printing more (quite the opposite actually). This makes it harder for Chinese companies to do trade, not easier, so I don't see what your point is.
However, if the RMB is overvalued (meaning they say it is worth more than it is actually), then capital controls are very necessary. If the RMB was undervalued, then you would need more controls in the opposite direction (for money coming in) to prevent arbitrage.
Right now the RMB is overvalued, but not by much. Maybe it should be 7 or 7.5 RMB/dollar.