I would think that it would be on the easier side to survive an attack from this thing, maybe, but harder to beat it in a fight, as any present danger that you pose to it can kind of just be circumvented by it choosing to fly away and then hit you when you're unawares. So I think hunting strategy would probably play a pretty big factor in this as well.

It depends on how this thing attacks prey. If it's a bird of prey, I'd kind of assume that it would dive prey and scoop it up, rather than landing and then attacking it's prey, and it's much harder to dodge a large bird than it is to kind of, fence away chicken-like pecking, as you've kind of described here. Much like how pelicans dive bomb surface fish.

I think it's also probably more likely that this thing would snap at you compared to pecking, which is probably going to be harder to dodge, depending on how much it opens its mouth, and what angles it tries to hit you at. Vertical snapping is pretty ineffective at hitting vertical targets like humans. I'd imagine it might be pretty capable of flesh wounds, though.

I agree that you can probably survive being stepped on by this thing, but some of the artists' renderings have claws, and in combination with the pressure and even just the size and probable strength of this animal, I'd imagine it could hit you with a pretty large gash, which might kill you without medical attention. Let's also consider that, even though you can experience a car rolling over you, and cars routinely weight more and spread their force over a similar surface area, a better analogue, along those lines, might be if we dropped a car on you, tire-first. If this thing decides to step on you, it's not putting down just 250 kg, it's putting down 250kg, plus momentum, plus muscular force.

So, overall, I'm not quite as optimistic of your chances as you seem to be.