Why did she get the endorsements? Did she promise to end Medicare or Social Security or do whatever the Republican platform is now? No, it's because she's not Donald Trump and these people think he's such a dangerous person to make president that they're willing to endorse a Democrat in the hopes it'll convince other Republicans that they should vote for Harris.
Is that self-own?
Yes, being so unthreatening to fascists that they vote for you and endorse you is a self own, and should make all Harris voters rethink wasting their vote for a bush era Republican.
If these people were fascists, why wouldn't they just endorse Trump?
Maybe, as some of them have said, they fear the fascism Trump promises and are willing to put aside any other policy disagreements to try to end this threat of fascism in America
Or simply, they failed to gain Trump's favor. They're fascist, they fully support genocide, that's not in dispute. They just don't believe the trump version of fascism enriches them as much as Harris would.
The imperial capitalist class has infighting, it has factions, because they are (occasionally) in competition with each other. But they have general consensus on exploiting the working class and other countries.