The article uses, as do you, a meaning of inflationary based on percent new coins added, but that isn't correct.  Inflation could also occur with fewer coins, with higher monetary velocity, or it could NOT OCCUR, with more coins, but with usage increasing at a similar rate as new coins.

There is also the "latent inflation", which is existent but yet to be realized in price levels on the street, and this is typically seen when governments start printing money like crazy.  I suppose there could be some similar thing with bitcoins.