The HUD has it's limitations. To think that it's the greatest thing since sliced bread was invented is silly.
Field of view issues. Lighting intensity issues, jumpiness of Flight Path Vector in turbulence, etc, etc.
Sliced bread was certainly a noteworthy and useful development, but it hardly compares to the magic and precision of HUD.
There are countless single-seat military aircraft flying around using HUD as the primary flight reference.
Again -- these were not inexperienced crewmembers and it's highly doubtful that the CA was new to flying HUD.
Do you really think that the use of HUD will turn out to be
causal in the accident report?