That's such a fucking stupid take from someone that doesn't even have a grade-school understanding of politics.
The Republicans endorsing Harris don't like her, and they don't agree with any of her policies. They probably do agree with much of the bullshit that comes out of Trump. On the other hand, the Republicans endorsing Harris genuinely believe in America, and in the idea of democracy. They clearly see that Trump is an enormous threat to democracy in the US, and that he's doing everything in his power to break the system that they believe in, even if his specific policies are things they agree with.
Whether I like Bush Jr., or Cheney (either one, really), or George Will, or any other Republican endorsing her, or not, they are still people that believe in the rule of law. Trump does not believe in the rule of law. These Republicans largely believe in letting voters decide, even if they'll jerrymander the shit out of districts. Trump does not. These Republicans don't believe that this country can survive a second Trump presidency, and they would rather lose the Presidency, the House, the Senate, and possibly a few seats on SCOTUS, than watch our democracy die.
Anyone that thinks that it's going to be only 'criminals' that get deported forget that crossing the border without documentation is a crime. Yeah, it's a misdemeanor, but it's still a crime, and the Trump administration is still going to deport them when they can.