It all sounds good on paper but I think there was more to it than that. They still used their short arms to hold prey I believe that can be seen in the claws the forearms had. Yes the bite was the most likely to kill but holding the prey while it ate had to be present too.
Human skull evolved along with two-legged walking, study confirms
The evolution of bipedalism in fossil humans can be detected using a key feature of the skull -- a claim that was previously contested but now has been further validated by researchers. Ref. Source 9g.
I can see the fact that the head resting more upon the spinal cord than just in front of it as one achieves true bipedalism compared to still being more on a for legged stance. I think this information can help scientist with the study of evolution and how it all came to be.
How dinosaurs may have evolved into birds. A possible genetic mechanism underlying the evolution of birds has been discovered by scientists. Studies of dinosaur fossils that show bird-like traits, such as feathers, light bones, air sacs and three-digit forelimbs, clarified evolutionary kinship of birds and dinosaurs. However, identifying genomic DNA changes during this evolutionary transition has remained a challenge. Ref. Source 2f.