Who would have guessed that they were all communist, fascist, Marxist RINOs?
Obviously these former elected officials, military leaders, national security experts, etc from every administration in the last 40 years are all just trying to destroy America.
Being recognized as the only sane choice by people across the political spectrum and by nonpartisan organizations that rarely if ever endorse presidential candidates is generally going to be helpful for a campaign.
While there are plenty of people on Lemmy acting like this is a deal breaker, I highly doubt any of those people were ever going to vote for Harris.
And even if there is a nonzero number of votes lost to third parties or staying home because of this endorsement, those lost votes are almost certainly less likely to be in battleground states, and are only worth half as much as any independent or republican leaning votes that would otherwise have gone to Trump.