There is context and nuance to everything. If you think this situation is ALWAYS creepy then I’m afraid you are objectively incorrect.

Children walk up to each other on a playground and butt in and make friends happily. Why do you want us all to be boring robots that never interface?

In what world is it creepy to overhear somebody saying something in a public place? Have you ever been in a social situation before?

Not really. If you were discussing with somebody about some terminal illness you were raising money for and somebody approached and said: “Sorry, but I overheard what you said and I’d love to donate, if that’s okay” that would not be creepy in the slightest.

There is a difference between ‘overhearing’ and ‘purposefully spying’

This is definitely one of those ‘creepy if ugly’ moments. If he was a handsome guy, it would be romantic and has almost definitely happened in a million Hallmark movies.

“This is how conspiracy theorists actually think”

I’m not sure why this generalisation was required? Many ‘conspiracy theories’ have been proven to be true, and not ALL theorists believe ALL of the theories. It’s easy to discredit somebody when you label them something and then say that those that are labelled are idiots.

edit- downvoting something without replying to it is how you get an echo chamber