I would have approved that edit. As a general rule, edits to improve titles are not considered too minor and should be approved, assuming they significantly improve the ability to draw users and outside visitors to the post. This means the edit to the title should have some meaning. If we're fixing a spelling error or rewording something so it's less confusing, approve. But if someone is changing a word from one synonym to another synonym of equal quality where the improvement didn't clarify the title, then perhaps a disapprove would be okay.
But any edit that improves a title should, as a general rule, be approved. Here's why:
Not only do titles grab our attention, but they play a huge role in SEO. A user searching on Google for "How to be found by headhunters" may not click on the link if it looks unreliable due to major typos, or in this case, wording that just doesn't make a lot of sense.
A variation of this particular question was also asked on Meta Stack Overflow, and here's the answer posted by Jeff Atwood ♦:
I just noticed these were title changes!
In titles, I think it is much more important to get key words correct -- so in the case of title edits, yes, these are OK and I would approve them.
If they were trivial body changes, I would be much less supportive of this, per http://blog.stackoverflow.com/2009/04/in-defense-of-editing/
The bold emphasis isn't mine. That's all Jeff. SEO is something Stack Exchange considers very important, and our most powerful Stack Exchange feature, the editing feature, is what helps make sure a Google searcher clicks our link and not someone else's. Hope this helps clarify! :)