So let's sum up, i am a legendary, i have 1236 posts, one post get flagged with a first part copied , modified and pasted and then 54% of genuine written text and that is it ! Banned for life. No slap on the wrist ? no warning . ?
I don't think your rank and the many posts you wrote over the years should serve as an excuse for what you did. In fact, if you go back a week or two you will find numerous cases of people getting banned for copy-pasting (including other high ranked accounts).
Yes, there is no warning about plagiarism, and people who have committed such a violation are almost always permabanned. What's worse in your case is that you have changed small parts of the first paragraph (
adapted in your own words), which means that you have done this copy/paste thing quite deliberately.