I'd speculate it's the element of surprise. Ideally the pause would do nothing to the game. (It could be that the game has some glitches but let's assume it's

I'd speculate it's the element of surprise. Ideally the pause would do nothing to the game. (It could be that the game has some glitches but let's assume it's solid.) Then one could assume that the pause does nothing regarding the AI players. But that is not true because the AI itself is not paused (I assume) and it has to handle this unusual input. This might throw off some versions of it and it probably learns how to handle the pause and how to use it to gain a small advantage. So it's all part of the game. Similar to when a human team uses the pause for tactical purposes.