The only reason I can think of for the accelerated S&P 500 inclusion of SpaceX is a pump and dump
To be clear, S&P hasn't announced a decision on this yet.
S&P don't get a choice around whether they announce their methodology or not.
That said, the rule change at the NASDAQ 100 doesn't seem to have impacted pricing or allocation. I can't imagine that many people are that concerned about this. (I posted the public-comment request from S&P to HN [1]. The response was crickets.)
I don't mind having a small bit of exposure to them, I just don't want the outsized share they seem to be trying to take for everyone.