That has changed and AI's 'view' is now restricted.
From the FAQ:
> Q. How does AlphaStar perceive the game?
> A. Like human players, AlphaStar perceives the game using a camera-like view. This means that AlphaStar doesn’t receive information about its opponent unless it is within the camera’s field of view, and it can only move units to locations within its view. All limits on AlphaStar’s performance were designed in consultation with pro players.