You make valid points but I think you are also missing others point. You state "should" in your statement which indicates you are assuming, whereas others have seen him play that position and he was dreadful. Not every defender can play every defensive position, just like not every midfielder can play anywhere in midfield or in every teams tactical responsibility model. I have seen very little of Otamendi at RB and have seen a fair bit of Pablo with the EDS, my opinion from what I have seen leaves me 50/50 its not quite as cut and dried as you make out IMO
Your right about me assuming. That's because there is very little in the way of performance from either for me to judge. Apart from a few games some years ago, Otamendi hasn't played RB.
The young lad hasn't played at all outside of the EDS. Hes only 18 so that is to be expected.
I don't see an issue in assuming and/or using Otamendis experience in the game as an argument, when neither have ever really played at the level we are as a RB you can't really use ability as the fundamental point to the debate. Nobody really know much about their respective abilities as RBs.
If Manuel has to make that decision between Maffeo and Otamendi he will be using his experience to make a judgment and will also, essentially, be assuming the outcome.