Thank you, Boris. You understand the model correctly and now I see what you mean. Yes, solving for M in UT and then applying PPP to get $ price would be a more correct approach. However, the main idea of the article was to introduce our model which accounts for all the periods — from today to infinity. In this respect, it is still valid.
BTW, Weber says that equation 9 is not a correct approach since the left and right-side denominations simply don’t match. Tokens vs. $. Nothing more than that IMHO.