Part of the article by NutLoose reported: "Apaches are considered robust aircraft proven to operate from the decks of ships, and are typically able to withstand strong winds".
That is all well and good if they are lashed to a deck, or in this case to any tie-down points in the tarmac. I assume this one wasn't lashed down?
The Apache doesn't have a particularly wide wheel base and probably has a reasonably high CG combined with a fair bit of lateral windage area and hence overturning moment. So left unsecured, I suspect it would topple in lower wind speeds than various other helicopter types, no matter how "robust" it may be.
I wonder how much contribution of the wind blowing over rotors has to the total overturning moment? I assume it is normal practice to park helicopters with collective in a 'neutral' position??