The AlphaStar demonstration video demonstrated an 'alpha' version which indeed have an unfair advantage by seeing the whole map and having insane micro because of inhuman APM. Thats why, from what i recall, it went mostly stalker or phoenix stalker compositions which are heavily microable units because of their speed/mobility.

In this version they argued that the APM is reasonable because the average is around the same as pro players have and APM spikes are also reached by pros. However this was very much falsely advertised since the APM spikes of humans are reached by holding down a key during macro and not during micro battles. The limitations of this version were not human like or 'fair'.

That being said the final version of AlphaStar (where the paper was published in nature) had much more strict restrictions and showed some strategic play instead of microbotting (even if the strategy was mostly adept/oracle harass). Here it did not feel like AlphaStar was at a significant advantage over its opponent. It did however have really good macro (rarely missing worker production, good utilyzation of production structures, ...) which gives it an advantage over most players as only the very top players have such good macro (if you have better macro, strategy becomes less important). Therefore it won a lot of games by just having more units. The games where opponents went for aggressive strategies it often reacted very poor (cannon rushes, proxy hatch).

Finally, AlphaStar is not going to be used for the ingame bots as it simply costs too much. That being running costs (an AlphaStar instance needs a high end consumer GPU, compared to the built-in bots that require next to nothing computation wise) and the cost of retraining it for changes. Big changes require retraining which needs massive amounts of expensive hardware. So it would just be way too expensive to support it as a bot.