I was one of the reviewers who rejected it, so here's how I looked at it.

There's nothing wrong with trying to improve an old question, but I tend to apply tougher standards.  On a new question, improving it can help to get it answered.  Bumping an old question tends to steal oxygen from new posts.  So an edit should make more of a difference than making a long-inactive question prettier while its buried on the site.  These are the kinds of things I look at:

 - How old is the question and when is the last time it had any activity?  Is it likely to attract a lot of future activity?
 - Is it still relevant (is the software or hardware still in use; are answers applicable to current versions if it is; etc.)?
 - How useful was it when the question was fresh (votes, views, comments)?
 - Are the answers useful and consistent or did it attract a motley collection of low-quality or conflicting answers?
 - How useful is the question and how clear is it?
 - Might improving and bumping the question attract new answers?
 - Might improving the question make it a significantly better resource if the information is "timeless"?
 - To what extent could the question use improvement and how much of the obvious improvements does the edit accomplish?

That question struck me as a low value, low priority thread that was already answered and probably wouldn't benefit from bumping.  It also seemed unlikely to be attracting a lot of future views.  

Sometimes on a question like that, I approve the edit if somebody invested some time to polish it into a gem.  I assume that if it was that useful to them, maybe it will be useful to others, as well.  

In this case, the only thing improved was the title, and that didn't seem worth bumping the question.

PS - At review time, I hadn't noticed that you had provided an answer.  Authors of answers often want their answer viewed in the best light, and want the question in the best shape it can be to attract viewers to the answer.  If I had noticed, and the edit had been a little more thorough, I probably would have approved it.  If you think the thread is still useful and want to take another shot at it, give it another go and polish more than just the title.

Update: Here's an example of another old post (6 yrs old), where I approved a title edit only: http://superuser.com/review/suggested-edits/625545.

The question attracted 14 upvotes, 8 favorites, and almost 13K views.  There is an accepted answer that attracted 18 upvotes.  There has been recent activity.  The question could use a little polish, but has no issues that prevented it from being useful.  The title was awful, but the thread managed to be useful and attract a lot of readership despite it.  This thread is a resource that appears to still be relevant, and just a title edit made it more useful.