Here's the dictionary: https://en.wiktionary.org/wiki/opt-in

> The property of having to choose *explicitly* to join or permit something; a decision having the *default option being exclusion or avoidance*; used particularly with regard to mailing lists and advertising.

You're just using the term wrong. That's okay, I've used words wrong before, and it just means you've been presented an opportunity for learning a new fact.

But there's no argument to be had except with the dictionary.