It doesn't seem that hard to figure out to me. These guys are professional coaches. There are no VFLs, just VFNs. (Vol For Now)
CBJ needed to retain someone from the old staff. It's fairly common in transitions. I guess JG was the best candidate. The whole "not retained, RE-HIRED" thing is just part of the sunshine blowing that CBJ does. It was probably the best offer JG thought he would get at the time, and he took it. It's all good with me.
There is a reason new HCs bring their guys with them. Hart basically hired the whole "system." So, JG was on the outside looking in from day one. Once he saw how it was going to be, he probably figured it wasn't a good fit for him. He got another offer that worked money and career-wise, so he bolted.
It's not that big of a deal, really. It's just business.
Saying that he Re-hired Graham and not retained him was CBJ being gracious to and complimentary of Graham. I don't think that's sunshine pumping, that's being a good manager.