> Why not, it's true that I didn't spot any visual difference so maybe we can leave it for now ? 

If you agree there is nothing on our side to do, feel free to close the PR & issue. One thought is that we might consider putting a summary of our conclusion on the issue itself, so that it is easy to find if someone else stumbles on it.

> I feel bad about it... thanks again for your time and the detailed explanation, I learned a lot about CSP !

Not a problem at all! I love asciidoctor and use it daily, so it is my pleasure to be able to give back to the community in any way that I am able. Keep up the great work!