In Bitcoin the supply and availability of currency are decoupled. By funging or splitting a unit of Bitcoin currency into pieces you increase the availability for use while preserving the value of everyones holdings. Based on the supply and demand the price will fluctuate independently of supply levels.

My understanding is that regardless of how inflationary or deflationary Bitcoin is, there will be no effect on the availability for anyone to buy and sell.

If the USD was deflationary, then maybe it would?