It is structurally disinflationary, not just deflationary. Bitcoin is still emitted every ~10 minutes with currently an average inflation rate just under 1% of its supply per year.

The "massive risk" the IMF sees is that without central banks or even less influential central banks the IMF existence would be threatened.

If an economy grows at 2% and the supply grows by 1% it is in permanent deflation. For a country like el salvador with much higher growth, the deflation can easily be much higher

You were discussing "structural" inflation, referring to Bitcoin as a system, not relative to inflation of goods and services in a specific economy. These are two distinct economic phenomena that can influence each other but should not be conflated.

Bitcoin's supply doesn't become inflationary or deflationary "structurally" based on the growth of x or y economies. The word inflation is used for both concepts but, structurally, Bitcoin will remain an inflationary system until around year 2140... then block subsidies are going to to stop, no new bitcoins are going to be emitted and then you (or more likely our descendants) can call Bitcoin a structurally deflationary money. Hence the use of the word disinflationary, it currently is in the process of becoming a deflationary system by progressively reducing the inflation of its own money supply (through "halvings" approx. every 4 years).