My pet theory is that around Model 3 unveil, Elon was still thinking they could make AP2 work with MobilEye chip on board as a transitional aid (the EAP board still has an empty spot where MobilEye would have fit). That would have allowed them to quickly ship an AR HUD that would have shown identified objects overlaid on the HUD. As, of course, they could not show a Model 3 feature that Model S/X would not start shipping at the same time at latest...
Now that they had to implement everything themselves, and as EAP still shows the identification is not up to scratch yet, keeping that AR HUD unreleased made sense until AP2 matured.
So, by the time it came to AP2 announcement, Elon relabelled it the "unveil part 2" and unveiled the thing without the spaceship controls, because by then it was known MobilEye would not be on board and Tesla was facing many months of implementation work before suitable object identification etc. would be available. AP2 does not even today show objects on the instrument cluster as well as AP1 does, so driving an AR HUD would probably be impossible with it.
Just speculation of course, but would fit the HUD theory.