Maybe naive, but also impolite. Opening an issue with a passive-aggressive tone isn't likely to be productive.

That's really the problem here. Ignorance is excusable, especially in someone who hasn't got a lot of experience yet. Rude ignorance is never so, especially around a library on Github where, if it's really that big a damn deal to you, you can always just fork, edit a big "THIS IS NOT APPLE COLOR EMOJI" note into the readme, open a PR, and see what happens.

I think this misses the point, if someone doesn't understand open source etiquette then I would give them a friendly reply. Even if it was mentioned somewhere in the documentation, I understand that people can miss it.

It's just that if someone speaks to me in that tone, regardless if this is an open source project or if I'm working customer service for a product, I'll still think they're acting like an ass. It's not a huge deal, people act like asses all the time, but why not just raise the issue in a friendly manner?