Sorry, but you can't just wish away the actual timeline of the books, and read something into her language that exists in your mind only. There are quite a few authors who write in earlier time frames, and NO they don't assume the reader will transpose the dates because the book is published in 2005. Sue Grafton a mystery writer, purposely writes in the 1980's to allow her gumshoe the use of old fashioned research techniques. You really do sound a bit paranoid...it's fiction after all.
OK, regarding timeline let's use our brains in the other direction. If she wants to take a swipe at the American president on the first page of her book being published in 2005, she has no other way of doing it does she? I've read the books and except for the point she started the first one in 1980, the books never discuss what year it is. Time is measured by Harry's age and the Hogwart's school year and the stories are occurring in the "present" as you read them.