Is there a reason why edits must be 6 characters long?
E.g. a parameter in recursively copy only images and preserve path is missing 1 character.
Remember, when you suggest an edit, it requires multiple other people to look at it and approve it. The character limit is to prevent people from wasting time by looking at exceptionally minor edits. So, don't limit yourself to just a tiny edit: try to see if you can improve the post to a possible state of perfection. If you hit all errors on a post, then no one else will even need to edit it.
Once you hit 2k reputation, and thus your edits don't need to go through the approval process, you can make those tiny changes without the limit in the way.
The part about multiple people doesn't apply here (it only takes one user to approve; on SO it's two), but the character limit exists for the same reason -- they don't want people flooding the queue with trivial edits. In this case the best option was probably to leave a comment telling the answerer about the mistake, although it looks like it's already been fixed
The quality of an improvement can't be measured in characters. Especially a code snipple can be turned from wrong to right by changing a single character.
Forcing the user to improve parts of a question, which doesn't need improvements, will not improve the text. It will just annoy and cost some time.