There's a bit of confusion in some of the answers here. This is what I told the user responsible for that notice:
As noted in the FAQ,
If you are not comfortable with the idea of your contributions being collaboratively edited by other trusted users, this may not be the site for you.
In order to post or participate on Stack Overflow, you must agree to the terms of service here, specifically:
You agree that all Subscriber Content that You contribute to the Network is perpetually and irrevocably licensed to Stack Exchange under the Creative Commons Attribution Share Alike license. You grant Stack Exchange the perpetual and irrevocable right and license to use, copy, cache, publish, display, distribute, modify, create derivative works and store such Subscriber Content and to allow others to do so in any medium now known or hereinafter developed (“Content License”) in order to provide the Services, even if such Subscriber Content has been contributed and subsequently removed by You. Subscriber warrants, represents and agrees Subscriber has the right to grant Stack Exchange and the Network the rights set forth above.
If you cannot, or are not willing to license your work in such a manner, to allow others to create derived works by editing it, and to allow it to remain publicly displayed on Stack Overflow for the benefit of others, then you should refrain from using the site.
Now, we do ask that when editing something someone else wrote, you do your best to respect the author:
The vast majority of edits I see, I am fine with. But in the case where the original poster is unwilling to accept the edits and actively rejects them — please do not force the issue. It just leads to heartache. When in doubt, move on. There’s no shortage of editing opportunities, in fact, more are being written every minute. There are thousands of users who would appreciate reasonable edits that improve their post. Do not fight an edit war over a crumb of bread — there’s nothing there worth fighting for! It’s easier to just move on and get work done than create pain all out of proportion to the importance of the individual edit.
Generally, if you're polite when editing and when correcting their misconceptions surrounding it, folks will accept that. But if someone decides to make a big stink about editing in general, particularly if they're polluting posts and comment threads with it, flag for moderator attention and move on.