If the truck driver wasn't paying attention or worse, distracted by his phone, well, it wouldn't have mattered what she did.
I've encountered scenarios like that before where there's no left turn lane and I need to turn left, and there's traffic coming from behind. I have taken the lane and signaled if the traffic isn't moving too fast, but I've also waited on the right to let through traffic go and wait for a gap to make the left turn if it is moving too fast. If the speed limit was 50 mph, I might have waited on the gap.