... My claim is that both high inflation and high deflation are bad, and that both low inflation and low deflation are tolerable.
You have to use a clear definition of deflation/inflation before discussing it. Bitcoin itself cannot be deflationary since no Bitcoins are destroyed. Bitcoins can be 'lost' or otherwise stuck without access but that does not change the core of the protocol.
If Bitcoin is thus not deflationary, or at least nothing extreme (lets say below 1%), the deflation you seem to have in mind is decreasing prices. Well, that's the economy and not Bitcoin. Changing equilibrium is just what free markets are about. New balance will be found until market preferences change again.
The wacky thing is how intensely inflationary Bitcoin actually is in terms of supply.
In the first year, Bitcoin experiences a whopping 600% inflation. We won't hit 1% amortized inflation until another 11-12 years from today. At present we're still above 10% inflation.