On our site, voting to delete questions requires 2,000 rep. It takes a minimum of three delete votes to delete a question, and more if the question is well received. We currently have 85 users that have 2,000 rep or higher.
Since the question being discussed was voted +0/-9, I think it's safe to say that the question was not well received according to the criteria used for increasing the number of delete votes required.
This isn't directly related to your having high reputation on the site. The only relevant privilege level would be trusted user at 4,000 rep, but that only allows you to vote to delete poor questions sooner; it doesn't affect the weight of your vote. One vote is still one vote, regardless of reputation, and the same number of delete votes would still be required to delete a question. The only exception to this in the Stack Exchange system is that diamond moderators have binding votes, which take effect immediately, for reasons we have discussed elsewhere, but no Worldbuilding moderator was involved in the closure or deletion of this particular question.
I don't know why the system would have indicated that an additional nine delete votes were needed, and I can see no reason why it should have.
The only reasonable possibility I can see is that you somehow mistook the net post vote count for delete votes required, but I can't really see how that would have happened. The two should be quite distinct.
It's also worth noting that out of the people who voted to close (five community members) and those who voted to delete (three community members), you were the only one to vote both to close and delete. So the question ended up being deleted by the votes of seven different community members.
If you see something like this happening again or suspect that it might, I would encourage you to make screenshots and/or write down exactly what you do, and post that as a bug report. For the time being, I'm inclined to chalk this down to "one of those things that just happen" at the intersection between imperfect human beings and imperfect technology.
(And before you think otherwise: I'm not perfect either. Despite wielding a diamond.)