I love ya man, but you're pushing it here. Miami has a fantastic alum base of coaches from the 1980s through the 2000s, and I guarantee you that they are not all close friends with "really strong friendships".
Coaches go their separate ways. They have busy jobs, they don't spend a ton of time on maintaining past business relationships and turning them into really strong friendships.
Setting all that aside, the important issue is that when guys work together, successfully, it's called "coaching tree". Sure, we can criticize Golden for not firing D'Onofrio, but at the time of the hiring, both guys were qualified and had succeeded at prior jobs together.
When a former co-worker or shared-coach-tree candidate is hired, and succeeds, everyone praises the Head Coach for having connections and hiring good people. When it goes poorly, suddenly it's "nepotism".