However, I think you are being unfair to MIRI. Eliezer was using the term as as far back as 2007, four years before you mention it first being used in Oxford. So it wasn’t originated in Oxford. And given that many CEA members have read LessWrong, including Toby Ord, it’s seems a stretch to even say it was independently re-invented.
There’s only so many things you can call it, and accidental namespace collisions / phrase reinventions aren’t surprising. I was surprised when I looked back myself and noticed the phrase was there, so it would be more surprising if Toby Ord remembered than if he didn’t. I’m proud to have used the term “effective altruist” once in 2007, but to say that this means I coined the term, especially when it was re-output by the more careful process described above, might be giving me too much credit—but it’s still nice to have this not-quite-coincidental mention be remembered, so thank you for that!