I think the point is simply if the dividend is paid to themselves then short of corruption or mismanagement they can always pump back that money into the company when needed.
Say you have a household budget, and you have separate "accounts" for different purposes.
If you pay money "to yourself" for groceries, sure, you can always take it back, but you still have to feed your family.
Writing down that your budget for groceries is $0 (or less than whatever is needed) doesn't give you additional freedom.
Sure, they could reduce government spending, or they could reduce the dividend, and reduce spending more, but in any case, the size of the dividend relative to cash flow or profits still says something about sustainability of the present course.
The KSA, after all, can't issue debt in its own currency, can it?