IMHO, QR and EY are also losing, but they do not publish their results as far as I know. So the losses are far greater for the region than what IATA says.
You hit the nail on the head. Even if financial results were published, their accuracy would be questionable because of the numerous combination of ways in which financials can be calculated. GAAP (Generally Accepted Accounting Principles) do not exist in the region. Generally speaking, there are two reasons why financials are published-- 1) for the stockholders (none in the region-- wholy owned by the Governments) or 2) because the Government taxman requires it (again, not here).
I suspect that the other major airlines (including Emirates) have at least the amount of losses that Gulf Air suffers, the difference being that these governments have deeper pockets and other priorities.