Also, if it went the other way, there would be gripes nonetheless: if she didn’t endorse you would have gotten “So much for vote blue no matter who” or something similar.

The outcome has been determined: El-Sayed the nominee of the Democratic party, and rather than than fracturing the party and giving the Republicans (and Trump) the win, they chose to get behind the (progressive) candidate that was elected in the primary, rather than pulling a Cuomo.