It's not entirely clear from the article. I can feel the pain of the maintainers if this was suddenly dropped on them. But the article slightly hints at that it

It's not entirely clear from the article. I can feel the pain of the maintainers if this was suddenly dropped on them. But the article slightly hints at that it was repeatedly communicated that werror will be enabled over a long period time. If this is the case they don't really have any grounds to complain.