That's how a lot are spinning this, and she doesn't endorse anyone (not even third party) because she's pointing to the bigger picture. However, I do think she's subtly weighing the options with the line "With this in mind, my main message to Americans is to remember that you cannot only settle for the least worst option." Read it carefully, along with what follows it about not quitting after a vote.
Vote third party as a message if it makes you feel better, but just like those voting for Harris - you better not stop there.