Jack just answered me on FB, management called him:
They did. Hadn't heard from them in close to two years before that phone call. No need to go into the details of that ridiculous exchange. I wasn't available to do the gig because as I said at the time, "I know Nelson Mandela is a very good man but I'm not going to miss the birth of my twin daughters for anyone. I'm sure he'll understand."
In the first place, could looks nice that they called him for the Mandela gig, but this sentence:
"
No need to go into the details of that ridiculous exchange"
Makes me think it wasn't that nice, maybe it was something formal and he detected wasn't a honest request, or was still hurted, and already move on on his mind.
Of course being a dad very recently makes it a good excuse to say no, but I guess he would had said no anyway, specially by what he said about that call from management.