Bostrom talked about the paperclip maximizer (as it's commonly understood) in a 2003 paper, but I can't find the exact date; and presumably he wrote the paper well before it was published (https://nickbostrom.com/ethics/ai)
Yudkowsky wrote:
I wouldn't be as disturbed if I thought the class of hostile AIs I was talking about would have any of those qualities except for pure computational intelligence devoted to manufacturing an infinite number of
paperclips.
Bostrom wrote:
It also seems perfectly possible to have a superintelligence whose sole goal is something completely arbitrary, such as to manufacture as many paperclips as possible, and who would resist with all its might any attempt to alter this goal. [...] Another way for [misalignment] to happen is that a well-meaning team of programmers make a big mistake in designing its goal system. This could result, to return to the earlier example, in a superintelligence whose top goal is the manufacturing of paperclips, with the consequence that it starts transforming first all of earth and then increasing portions of space into paperclip manufacturing facilities.
These quotes read as if Bostrom is the original source, and he's talking about outer alignment failure, not inner alignment; Yudkowsky's quote doesn't give any context, which may be because he's referencing Bostrom's paper. (If he's referencing an earlier thought experiment that he wrote, then where is it?) This looks like evidence that Yudkowsky's memory is incorrect—the paperclip maximizer is due to Bostrom, not him, and it wasn't misinterpreted. But it's possible that Bostrom himself misinterpreted an earlier thought experiment by Yudkowsky (possibly in a private or non-recorded conversation).
I looked into the exact dates here and found some additional evidence.
Bostrom's Paper: Conference Date Established
The paper was presented at the 15th International Conference on Systems Research, Informatics and Cybernetics (InterSymp 2003), held July 28–August 2, 2003 in Baden-Baden, Germany. This date comes from the Open Library catalog entry for the proceedings volume.
Wayback Machine snapshots of Bostrom's homepage narrow down when the paper went online: it is absent from the July 29 snapshot but present on th... (read more)
These are in any case distinct ideas, and one of them shouldn't argue against the use of the other on historical grounds. The framing of the edits on the LW wiki is terrible, with retagging of existing posts and excision of the concept of "paperclip maximizer" in its actual form as it in fact came to be (even if not originally) from the record. I get the point that in some ways "paperclip maximizer" could be misleading, especially when intending to convey the lessons of "squiggle maximizer", but it's still its own thing with its own meaning and its own lessons.