What does theymos have to do with tihs? Theymos tries to keep this forum "as free as possible", so he's not going to get involved in who gets into a signature campaign.

DarkStar_ has to choose 4 out of 150 participants, many of those 150 users have very good post quality. There's a strong competition, and it's entirely up to DarkStar_ who he chooses.
So far, I can only say he's picked strong candidates, and from what I've seen, ChipMixer trusts his judgement on this.