This isn't inflation, it's just a miscalculation. Again, if the extra 4.5mm changes your buy/sell/hold outlook on the coin then you should sell. But, the success of the project doesn't hinge on the answer, so it's not a big deal like you are suggesting.
What is a big deal, and I agree with you on, is why the team hasn't addressed this question.
Tell me how the market would respond if a billion more coins were added at the next halving. We assume value (market cap) stays the same. The price would gradually be worn down as those coins are added to the exchange because everyone who owns it is already bought in and everyone mining needs to sell at whatever price they can get. This is the effect on current coin holders unbeknownst to them. It's real no matter how much you downplay it.
Stop with the straw man arguments. Yes, if it was a billion coins it would be a big deal, but it's not a billion coins.