Inflation is included indirectly in the Power Law. 
The price is based on the observable that is whatever Bitcoin is valued at that particular time. 
In creating the model data from 2010 is used so it contains, indirectly, already the inflation over the last 15 years. 
The main matter is that inflation is small in comparison with the power law growth. 
It is difficult to think in non linear terms. 

Even if the inflation is going higher in the next 10 years (I'm not sure is the case) it needs to be comparable with Bitcoin gains projected for the next 10 years to affect the price trajectory. 

Bitcoin gains are about 44 % right and are going down to about 26 % in 10 years. 

Any reasonable rate of inflation would not affect the behavior of the power law much (and as I said a reasonable rate of inflation is already contained indirectly in the model). 

What people do not realize that gains due to inflation are not free money. It is exactly what we don't want Bitcoin to do.