And he wasn't even going the sort of speed that would have made avoiding the spectator unachievable. In fact he basically just accelerated straight at the spectator in question.
What the absolute 🤬 was Jari-Matti thinking? 🤬
Watch it again. I don't think he saw the spectator.
When he hits the ditch, all he's thinking about is keeping it pinned to not get stuck. Every spectator there realizes this, except for the one idiot.
When the car pops up out of the ditch, it quickly rotates 90', at the same time, the windshield becomes completely blocked by thick white steam from under the hood.
No one else is standing where the person who got hit was. He was all by himself. When the car hits the ditch, everyone backs up. This fool doesnt react until the car is nearly on top of him. There is moment where the camera loses sight of the action, likely due to the camera man taking evasive action himself. When the camera picks up the car and the guy again, the guy looks like he's either fallen over, or is trying to pick something up off the ground (his camera maybe?). He looks like a bumbling fool before he gets hit. And the whole time, the windshield is covered in steam.
My guess is this was a guy trying to take either a photo or video. He wanted to get up close to the exit of the corner to capture some nice oversteer action, maybe a tire drop into the ditch; he just got a lot more than he was expecting

Again, no one else was dumb enough to be standing where he was. I'm also guessing that there's a very good chance he'd had a couple of drinks, hence the stumbling and bumbling.
Honestly I don't fault the driver here at all. Dumb rally fan is dumb. Classic idiot ruining it for everyone else.
Edit: pause the video at 10 seconds, just before impact...what do you see. I see windshield completely blocked, and guy bending over to pick something up off the ground when the car is less than 5 feet away.