And the women were believed. Their accusation was not dismissed, but taken seriously, an investigation started etc.
However, that is not the same thing as "accusation = guilt".
We live in the former world, not in the latter. Fortunately. And I am pretty sure he was describing the former, not the latter. And if he was describing the former, then he was simply wrong.
You seem to be using a different definition of "believe" to the rest of the English-speaking world [1]. Belief usually comes after investigation, it's certainly not a prerequisite.
If he meant that accusations should be taken seriously and investigated, those words were available to him. He chose "believe", and now I choose to believe his accusers.
As for the world we live in, you're thankfully correct (for the most part). Kimmel was an activist who wanted to change the world, and they do occasionally make progress in that direction [2][3].
However, that is not the same thing as "accusation = guilt".
We live in the former world, not in the latter. Fortunately. And I am pretty sure he was describing the former, not the latter. And if he was describing the former, then he was simply wrong.