You don't understand atheism. The atheist assumes nothing. The atheist doesn't assume there IS or ISN'T a God. The atheist simply rejects God period as there is no proof that one exists. The atheist rejects faith alone as proof of His existence.
Its somewhat off topic, but its actually you that doesn't understand the definition of "atheism".
Atheism is defined as a lack of belief in god(s). That belief structure is based on a fundamental assumption... that there is no god. You are describing agnosticism, which is defined as "a person who believes that nothing is known or can be known of the existence or nature of God or of anything beyond material phenomena; a person who claims neither faith nor disbelief in God."
The larger point is that, just as the existence of god is unknowable to us, the existence of a tweak to the source code is unknowable to us. Yet you accept that, because it could exist, it likely does exist. That is a faith-based argument. Therefore, it is no more or less logical than an argument that god is dictating the distribution of BPs.
By contrast, basic statistics indicates that, in any large population of players, there are going to be some who have the unequal distribution described by the OP.