Could it have been the Beemer driver's fault?

The truck wasn't completely out of the travel lane and no visible evidence of triangles out.

I realize there isn't enough shoulder to get completely off the road in that area and maybe he just broke down and maybe he hadn't had time to get them out or maybe didn't feel it was safe for him to do so. Or maybe he needed to stop for some non-break down related reason and chose that spot to do so.

What he said......at the end of the day not enough information to say one way or the other.

 

Hard to tell but it thought it was out of the travel lane, barely.

Not a place most would stop if they could avoid it but it's basically a rear end collision. Run into the back of a large vehicle and there's a pretty good chance you weren't paying proper attention.