That is
VERY wrong.
China did not pump 118 billions in HKD to saves HKD, It's easier to fight Soros in HKSE rather than in SHSE or SHSE, because doing so, you will need to devalue RMB, which is what China do not want.
Second of all, fighting Soros in Hong Kong would mean the Chinese can fight Soros using a combination of HK FX and Chinese FX, do bear in mind, this is before any exchange deal offered between RMB and HKD.
I will not comment on this as this is basically discussing what Soros is or isn't going to do if in the case he successfully hedged HKD. The only person in this world know exactly what he is going to do is Soros himself.
But I will just leave you with this note. After HKD, which other currency in Asia is vulnerable enough and have profit margin good enough to short? Yen? They are already very deflated, shorting yen is like shorting cents. Singaporean Dollars? They are stronger than HKD and If I was soros, I wouldn't touch it after I hedged HKD, because I will bleed a lot of cash doing so.
What you say underlined did not make sense, you are not investing or shorting stock in China Stock exchange, you are shorting the currency forex, those are different.
https://www.thebalance.com/what-it-means-to-go-short-in-investment-terms-1344960
https://seekingalpha.com/article/4054567-china-time-short-yuan
Virtually no one in Hong Kong Stock Exchange believe that, as I said, if China did not stop Soros in Hong Kong, China would have a more difficult fight later, and if they do so in Hong Kong, they can use not only their own Forex, but Hong Kong's forex as well. It's a better to deflate HKD, which is pegged to USD anyway, than deflate RMB. Hong Kong Dollar can self regulate (Because of the pegging interest rate) while RMB can't.
But well, you can think China think of Hong Kong is a part of China, but economically, it have nothing to do with dealing with Soros. It's basically a strategy, which give you a better chance to win..
Again, you have the problem with the poster before. Shorting currency forex is not the same as shorting a stock.
To short a stock, you will need to borrow stock that you do not have. To short a currency, you only need to place a sell order. And Soros can open an investment company that only trade Currency, but not asset. Which is exactly what Soros did in Hong Kong. And since you can exchange CYN to HKD in 1998 China, (I think the exchange rate is somewhere around 1HKD : 1.2 RMB, but don't quote me on that) which mean you can dump HKD into altering the exchange rate and interest rate of RMB
The only thing you need to notice when you short a currency is pair rate, and China hold a 2% different pair rate between any currency to RMB, which is harder to short, but it's not impossible, especially if you have money. And again, China in 1998 is not the same China now.
In short, he don't need to buy or sell RMB, as long as he can buy or sell HKD or any currency with an exchanged value in China, he could short Yuan.
Some would argue if the stock market already did not have a grim outlook, it's impossible to short anything (Not stock, not currency, not anything) and Soros could not have make that happens.
He IS a business man, he is no dirtier than any other businessman, would you think there are "Nice" businessman out there will consider the feeling of any employee or people that is affected when he make the decision? Give me a company name and I can name some of the stuff they done driven solely by greed and ignore the suffering population, I mean any company, US, China or anything. Do you think Jack Ma build his empire today by being nice? Or by being a Buddha? How many hostile take over that left how many people jobless before he can build Alibaba the way it is today?
If you think Soros is unethical, you are probably right, but then you cannot be a nice guy and work in business, that is like Business 101.