I don't know the business/baseball operations side of things, but I definitely think Frederick was a better location for an O's affiliate than Aberdeen from the perspective of having a foot in the DMV and competing for fans with the Nats.
Growing up in MoCo, going to Frederick for Keys games was an easy and accessible way to experience professional baseball that strengthened my connection to the O's. No one from DC is going to Aberdeen.
Maybe the O's thought they preserved that presence with an affiliate in Bowie. But in all honestly, I don't think the edge of PG County really captures the MoCo/NoVa crowds.