I think Clark's point is that they're effectively stuck with it - he's telling Airbus that if they (Emirates) hadn't spent so much in infrastructure, they'd have already pulled the order, but there comes a point where the cost equation goes the other way.
What it does do, is explain why the order book has largely stalled - those carriers which can afford the non-airframe spend have already signed up; those that can't, haven't. Hence it seems to me that further orders (or lack thereof) have less to do with the cost of the aircraft itself than with related costs.
That said, it does seem curious that the spend already made on making things A380-ready, could not be applied to other large aircraft (748??) (clearly other than things like sims and cabin training mock-ups). One wonders how many A380 sims EK must have ordered already... and if any are already in Dubai?
What a mess.