No way that you can blame the snowboarder 100%, it was an accident and he definitely took responsibility and asked the kid if he was okay, the dad on the other hand didn't even care. Sure, the rider who comes from above has to look out but if that idiot of a father stopped in the middle of the slope and just pushed away his kid without looking he is the one to blame. HE has to take responsibility and look out for his kid, HE knows that he is in a public ski area, HE isn't the only one aloud to use the slope. HE should know better/be more careful than to just push out his kid in the slope.
How many times haven't you skied and a gaper or a kid has just made an turn you definitely couldn't see happening, or not making a turn which results in that the gaper/kid moves in to your planned way down. In those moments, its you who has to turn away, which clearly the snowboarder does when that little girl comes in his way. The snowboarder could have gone in to the dad and the kid even if they were standing still and I would still consider them to share the blame. Once again, other people is using the slope and if you are standing in the middle of it and something happens above that makes a skier/snowboarder to make a sharp turn, brake or such he should have the place to do that.
The dad should have been in a kids slope. And you talk about speed, clearly he wasn't going warp. The dad is also standing, what it looks like, beneath a corner and where the slope seems to get a bit steeper which makes him harder to see.
The snowboarder has some kind of responsibility as well but not nearly all of it. I would say 50/50 maybe, and the dad definitely doesn't see his part in it. You shouldn't take your kid out skiing in big slopes if he isn't ready. Even if the snowboarder hadn't crashed in to him, what says that the girl hadn't? The kid is going straight over the slope and would probably didn't make a turn or would be able to move out of someones way, rather to get in everyones way. A kid that young can't make perfect turns and he would zig-zag his way down over the whole slope, he is going to be an obstacle.
since they share the blame, the snowboarder came out as the good guy for asking if he was okay and the dad comes out as a fagbitchtitsidiot for acting like he did.
Sorry for sounding retarted, but my english isn't that good and it is hard to wright so it makes sense when you can't get all the words right. Here is a picture of a Swedish falukorv.