Who knows? They only talked about a single election where people who were more sensitive to pain were more likely to vote for the other party than people who self reported as being less sensitive to pain. There were plenty of reasons in 2020 to vote against Biden and Trump. Maybe it just means those with more empathy are less blindly devoted to party.

Since emotional pain and physical pain are experienced similarly in the brain, maybe they felt a stronger sense of betrayal from the political party they typically align with and that resulted in a vote for the "other team" who they always felt had some good points anyway.