This is very smart of these folks because for just three companies, they can't ruin the trust and impeccable reputation they have built over the years. This decision alone is worth several trillion dollars.
Well, it might be a good decision but I think the possibility of Standard and Poor one day being worth trillions of dollars more than if they had included three companies a year or two earlier than when they inevitably join the index is absolutely zero.
S&P - https://en.wikipedia.org/wiki/S%26P_Global - is a business intel & analytics firm, not an investment firm. Their S&P 500 list just one of many datasets that they manage and sell. Cleverly trying to pick future winners and losers has little potential upside for them, and could put them into direct competition with many of their customers.