"And why is changing a "no" to a "yes" unlikely? Do interviewers never change their mind afterwards?"

It's not that they never change their minds, it's more that they usually don't. Especially after telling someone officially they're rejected. If a company rejected me then phoned me up two days later saying they changed their minds I wouldn't look too favourably on them.

"I'm mildly annoyed at the person in question, and I'm outraged at all the people coming out of the woodwork to defend him."

Personally I just think he's a weirdo who's clearly not that smart. But I've seen some people call him a "sexual criminal". I'm like WTF! That's a bit extreme. That's the sort of thing the outrage culture is describing.

You seem to be saying that changing the interview result isn't worth considering because it's not normal and would cause you to think poorly of the company, yet this whole discussion is about asking an interviewee on a date which is also not normal and causes me to think poorly of the company.

It has nothing to do with normality, just potential.

I haven't seen "sexual criminal" but rest assured that I'd object as strongly to that as I object to all the people defending this guy.