It's not a very good analogy. AOC has two choices in American politics: Democrat or Republican. She may not be a perfect fit for the Democratic Party, but she's significantly closer to them than she is to the Republican Party (even before MAGA).
Schwarzenegger had the same options. He would have fit fine in the Democratic Party, but he, for whatever reason, chose the Republican party; a political party that has been overtly racist for as long as any of us have been alive.
Maybe he had some good reason to throw his support behind the Republican party pre-MAGA, but it is still a valid criticism that he made that decision.
Valid, but I have to admit, it's not a very useful criticism. What's he going to do; time travel back and prevent himself from making that decision?