I'm not sure that answers his question. I think he was questioning where the regs say that ground training is not ground training unless it is intended to be used for a certificate rating, privilege or currency.
You'd probably do better suggesting out that under 61.51, nothing needs to be logged at all unless for those purposes, so why should flight or ground be any different. Just don't log anything. Or you might point out that the
Chief Counsel's office said within the past few years (I think with tongue firmly in cheek) that a checkout doesn't necessarily have to be training. Of course, if you refer to that, then you unfortunately wind up with, "A checkout is considered flight instruction if flight training is given during the checkout," which seems to be contrary to your view.