Semi trucks don't turn like regular cars and trucks do. They have to make wide turns due to the length of the trailers. That being said, I wasn't there so I don't know exactly what happened, but I really don't think any trucker wants a road death or accident on his record, intentional or not.
But yeah, if it was a four lane street there's really no reason he should have gone completely over the white line to make a left turn. I think if it were me in that situation and seeing a big truck pull out into the intersection, I'd probably slow down or stop if it looked like he was going to take up the entire street.