Steve, for what it is worth, as I have the 600 Cummins, I associate with numerous Entegra Aspire and Anthem Owners whom have the 450 Cummins in their coach's, 2014 thru 2017. None of them indicate that they have had any problems with their engines and several have 3 times the mileage on as yours does. Having oil sample is excellent and I am sure Dave Atherton can read this sample and tell you value of sampling firm and results it indicates.
This engine has a baseline sample and this is excellent history to have and continue. It gives you that internal view of all the functioning parts that you can continue to evaluate with ongoing sampling at future oil changes. It becomes the electrocardiogram of your engine.
This owner has provided you some outstanding data to make your decision on. He has also done his homework to protect the value of his investment.