Structural strength against pressure or stress and impact are different things.
Wind can lift solid objects way heavier (and with sharper edges) than a <900g drone. On the other hand, a hovering drone has no kinetic energy at all and will be instantly deviated/destroyed on hit as it offers no resistance, leaving a dent or a scratch at most. The planets kinda need to align for a drone to penetrate the aluminum, but it could happen; it's possible if it hits the precise spot at the precise angle. I'm not saying a drone couldn't do that, I'm saying there's no evidence yet.
The thing here is that there's no evidence that the damage was made by a drone, and as always, the media is demonizing the hobby for free.
In the end a drone hit a firefighting plane, it's not a fact yet (the fact is that a plane got damaged), but it's the truth everyone will believe and repeat from now on even if it's confirmed to be a drone or another thing.
DJI and Autel drones are already kinda banned in the US because potatoes, and more demonization worldwide will come from the NJ events, this plane and so on in exchange for nothing.
How many cars have collided with firefighter trucks or ambulances last year? Who knows. The other day a crazy man drove a car through people in Germany and I can still drive my car like nothing while thousands die each year in car accidents. No one cares, but beware of drones.
Only money and not safety (no one has died in the world by a drone accident) is behind drone overregulation and demonization, and the sooner the hobbyist realize (if there's anyone left that flies), the better.