Trump skipped debates all throughout 2023, so Biden has something he can point to if he wants. I don’t know why anyone thinks Biden would “fear” a debate with Trump so much, gives me too much 2020 déjà vu where some were basically saying the same thing and Biden showed up and obviously didn’t tank his candidacy at the three debates that year.
Biden can play it off that way, but the difference between a primary debate and actually debating to see who becomes the leader of the free world is vast.