Paying out higher (better) odds means you think they’re less likely to win
Edit: They were initially confused about how betting odds work, now they’re confused about how outcomes work.
William Hill is saying that Trump has a 65% chance to win, and the Democrat has roughly a 35% chance to win, and that Democrat is much more likely to be Kamala than Biden. There is absolutely no conditional involved in this odds presentation that would imply who has a better chance of beating Trump, as separated from the question of how likely the Democrats are to replace Biden.
I added an edit which is critical of your new assertion