You can counter by saying, "It's not designed that way" but Bitcoin is designed to accept whatever forks a concensus of miners accept, so it is possible.
Please elaborate/provide evidence. I have never heard of such a link or economic property that would demonstrate that volatility is impacted by the sign of the inflation rate.
And of course, miners already influence the money supply by choosing to sell or hold their supply, so they act as a decentralized form of the ECB/Fed/etc. Their less influential 'monetary policy' is probably much less harmful as well.
And it's important to understand what deflation is -- Bitcoin only appreciates when people assign more value to it. All things being equal, Bitcoin is NOT deflationary, whereas the USD is inflationary, because even with 100% adoption the USD supply is artificially increased, and the value eroded.
Then you must have been asleep during economics class when they covered the great depression.
Most modern currencies are inflationary and have taken steps to remove deflationary properties like the gold standard, because it exasperates volatility and economic bubbles. It promotes hoarding, which decreases liquidity and increases volatility.
It's exactly why quantitative easing is used to increase supply of money in order to maintain a specific range on inflation.
Personal attacks are no substitute for content and explanation; I'm trying to help you by giving a chance to better expound your original point.
For your own understanding, I would recommend reading the Monetarist explanation of the Great Depression: https://fee.org/articles/money-in-the-1920s-and-1930s/. There is also the Austrian Economics approach which is built around the fact that inflation was promoted to keep commodity values constant -- in reality, I think both Monetarist and Austrian economic factors played a role.
Most likely, I would guess the issue is that you don't understand the definition of volatility: https://en.wikipedia.org/wiki/Volatility_(finance)#Mathemati...
Please review these materials and explain how price volatility is related to the sign of inflation, or whether you meant something else. My assumption is that it is not, and I have seen no evidence to suggest otherwise. You can look at the most volatile years of US exchange rates and they were during the Jimmy Carter "stagflationary" era. You may be conflating volatility of a currency with volatility of other measures in an economy.