They didn't cheat on sc2 did they? They did in sc1. But regardless, with the breakthroughs in AI recently, I don't think they'd need to cheat on a hypothetical sc3.
I think "playing like a human" can still be an issue depending on the game. Until people want to play against AIs, there's not a lot of work put into making AIs human-like rather than just AI players.
Also there still Starcraft 1 AI tournaments which are interesting. https://youtu.be/gqggsFpTAt8
I didn't know they were still doing SC1 AIs, I always wanted to make one but never quite figured out how to get started.