I believe moderators do see a more detailed timeline view compared to what non-moderators see. But it is odd that there would be a discrepancy between the number of close-voters on a post.

The close review item for that post shows that the review was invalidated with one Leave Open vote. Perhaps there were other voters who voted on it outside the review queue, and this is visible to moderators?

I haven't yet searched Meta Stack Exchange for details on what extra information is visible to moderators on the timeline, though.

Perhaps a simpler scenario is just that Xander misread the timeline, since there are four users listed for the "deleted" entry just above the "closed" entry, so it might appear that Xander was the fifth close voter at a quick glance.

@TheAmplitwist There aren't that many posts on Meta SE tagged moderator-tools AND timeline. None of them appear relevant to this case…