Yes, churn is a metric. It's not always someone rejecting you. It could be that they just needed your product to solve a problem and then unsubscribe. They are not rejecting you but you've served the need and so they stop paying you.
As this stuff scales you need for think of churn as a cohort and start looking at why. I don't argue that. But, framing it as rejection is incorrect. Guess it depends on the service you're providing though. If it's something highly personal where you, the person are highly involved, then it might be rejection. But, I think that's pretty niche.
He's churned, but he hasn't rejected the service. He just doesn't need it anymore because his circumstances have changed. If he needs the service it offered, he could presumably re-subscribe to it later.