I don't think that's a good analogy. Learning a "real" instrument is extremely difficult and takes thousands of hours. Writing your own blog post without AI takes like half an hour.
It's not really because everyone learns at school. And in fact it only takes a few years (my kids are going through it now and I was surprised at how quickly they went from not being able to read at all, to having better handwriting than me).
It's like, learning a language is really hard. Learning your native language is super easy, barely an inconvenience.
So I think I would be more accepting if he said "sorry I can't speak English because it's a second language so I used AI to help", but he didn't.
I think you both had a different meaning behind the verb 'write'. You clearly refer to the physical act of writing, while OP refer's to writing as an author (ie be enjoyable to read), which most people never achieve.