Honestly I'd say randall is the one doing that.

  YC hackers are like Z.
  SpaceX is like Z.
  Therefore SpaceX is YC hackers (in spirit).

piotrSikora isn't literally asking why such a thing is a property of only YC hackers. He's asking why randall is using property Z to label things as 'YC hacker'. I don't think your jumping on his imperfect wording is very helpful.