Um, not necessarily I think...
This isn't just about the quality of the product "disposable chopsticks". It's also about the access to quality information about this commodity. And about trust.
If the information is restricted or simply of too low quality and people become aware of a risk here, chances are they will stop using disposable chopsticks. As you say, they will bring their own, or accept the use on non-disposable ones, possibly washed before use in their presence at reatsurants etc.
I mean it, most market operations is about acting on available information and trying to get a crucial piece before everyone else. If the public information avilable isn't seen as reliable, people will fall back on the age old trusted method of rumour. If so, they tend to adapt an over cautious behavior as well. It's like poor Dann no longer trusting the meat-buns. Is this because all meat-buns are actually bad, or the fact that all meat-buns are suspect, due to a deficit of information about them?
If a public starts doubting the quality of a commodity it's entirely possible they will drop it as much as possible, business very much being about trust in some forms. In that case the entire market for disposable chopsticks might well do a magical shrinking act. And most producers being honest isn't going to cut it, if the public don't trust the information circulating about them. And unless there is legal regulation and enforcement, you will always get some people scamming the rest by putting out shoddy products, cutting corners like crazy to make extra profit. Allow them to go on, and they can mess up entire market segments no end. This restricts business, which means there will be less of it.
Granted, disposable chopsticks alone perhaps won't bring the mighty Chinese economic miracle to its knees, but what if it spreads? And what if the Americans et al. buying all that produce decide Chinese stuff can't be trusted and give it a miss, buy American etc., just too be safe? They will be buying the more expensive stuff, meaning they can consume less, meaning less growth here, certainly for China, but they will be buying a form of safety, which is also part of the commodity.