I don't think it's overstating it too much. Even with the restrictions, the bots are still performing well above the capabilities of the vast majority of human players. The restriction on illusions and summons was also for the benefit of the players; the OpenAI team didn't want the bots to win through flawless micro skills. For point 3, even though the players didn't get to train against bots, they have the advantage of being able to learn and react accordingly. Since the bots can only learn when their models are being trained, they're trivial to beat if you use a novel technique that they haven't seen before.
If you want the bot to avoid winning by micro, you add delays, cooldowns on interactions, imperfection on clicking, misclicks, etc. on the level of a human pro.
In any case, simplifying the game is usually done to make training far cheaper.
But the human competitors also require large amounts of training in order to competently play Dota 2, and their training is not simplified that training in a similar way. I realize that "fairness" is not really the point of having humans play against bots, but doesn't it damage the usefulness of the comparison from having them perform a human activity?
The work I've seen recently from them on multi-agent play seems to indicate this is a problem they're very successfully working on. https://youtu.be/kopoLzvh5jY
