Definitely a valid question. The question is, as you said, basically unsalvageable, apart from massive editing. Sean, like you said, just edited to clarify that there was some conversation material, some off-topic questions, and just generally to make it easier to read.
So why the re-open vote? Tough question. There are multiple possible reasons: As Andrew pointed out, it can be accidental, but sadly, occasionally people will see that the post is better edited than it was before (or at least, better formatted) and think, "Aha, that looks nicer than it was. I guess we could reopen that," without taking time to seriously give the post a read.
Moderators do have tools with which they can determine if this is happening in a serial way from a single account, and we do have the ability to give a given user (after we have satisfied ourselves that it is definitely merited!) a review ban, during which time they will be unable to review close / reopen / whatever votes.
It's a good reminder to all of us that review queues are for just that - reviewing. The purpose of the review queues is not to amass badges, it's to give posts that are sent there a serious examination. Is this post on topic? Is it clear? Is it specific enough? Failure to do this is counterproductive and self-destructive. Which is why, if this kind of behaviour is repeatedly seen from a given account, as moderators, we apply review bans.*
When you see this kind of behaviour especially on a small site like this one, just flag for moderator attention and move on. (Be specific and detailed with any evidence you can see — don't just flag with
This post should be closed why aren't you closing it.) One reopen vote won't make a huge difference in the grand scheme of things.
*Obviously, this does not completely solve the problem, since users can still simply vote to reopen without going through the review queue. Without going into detail, there are other tools available to moderators to deal with these situations.