s&p is one of the few that didn't change their rules. if you buy an etf of a different index, they are legally required to purchase the same equities in the index, or that would be fraud.

from the article you linked:

The S&P 500 index committee decided to not shorten its standard 12-month period before adding newly public companies, in contrast to the decisions from the Nasdaq and Russell indexes about the mega-cap stock.

Many new SpaceX leveraged ETFs are debuting tomorrow so investors can hold the stock as an ETF with varying degrees of risk.

Unlike the S&P, index committees for the Nasdaq and Russell market benchmarks said they would update their rules. In the simplest terms, here’s what that means for core U.S. market index fund investors.

“If you want SpaceX, you’re not buying the S&P 500. You’re going to buy the NASDAQ 100 or the Russell 1000,” said Strategas Securities chief ETF strategist Todd Sohn on this week’s “ETF Edge.”