> is SpaceX actually worth $1T

Actually irrelevant to an index calculation. If your index manufacturer is taking this into account at any level, they're actively managing. S&P predates the modern active-versus-passive dichotomy, but it functions within it in practice, and despite being a leader of committee-based indexing philosophy, they've broadly found success by also being champions of passive management. And part of doing that is rejecting judgement over how the market is weighing this or that.

If someone is trying to bend the rules of my passively managed index fund to their will, are they trying to actively manage my passively managed index ETF ?