Yes, AlphaStar was already up 15 workers -- "build a Phoenix" would have completely shut down the prism and is apparently something that particular agent never learned how to do properly.

Camera management isn't part of that equation.

Though it is fair to conjecture that Mana may have won the earlier Blink Stalker vs Immortal game, if camera management were required.

Depends. If camera management soaked up a large share of the training capacity of the network, then that might explain why it failed to learn how to handle drop-harrassment.