As the post I was answering to just talked about converting the asterioid to sand, I assumed, that all of it would hit the atmosphere. But indeed, if in this way part of the asteroid misses the earth entirely, it would be a win. I was also a bit simplifiying/exaggerating. When talking about heating up the atmosphere, the consequences entirely depend on how high the thermal impact is going to be. If spread far enough, there could be a "global warming" which is below the limit for an instant disaster. (And when caused by a single event, would decay quickly)