No, it is not. It is Not An Answer to the originally asked question and therefore should be treated as NAA.
I will demonstrate it in an example:
Original Question (asked at 8:00am) written by Alice:
What is the full name of the president of the united states?
First answer (posted at 8:10am) written by Bob:
The name of the actual US-president is Barack Hussein Obama II actual.
This answer gets some upvotes. 10 hours later comes the next answer:
Second answer (posted at 6:00pm) written by the brandnew user Carol (obviously just registered to be able to react on the error) who has a reputation of 1 point:
I am a new user and can't write comments. So I post this as an answer.
There is an error in Bob's answer. He wrote:
<quote>The name of the actual US-president is Barack Hussein Obama II actual.</quote>
There is one actual too much.
The correct answer is:
<quote>The name of the actual US-president is Barack Hussein Obama II.</quote>
Within one hour three users upvoted this answer of Carol (It is his very first answer as a new user). Then a fourth user, Daniel, edited Bobs faulty answer and deleted the futile actual. He also set the NAA-flag to signal the moderator to delete this now useless posting. Some times later also Bob came across the site again and raised the NAA-flag, and also asked the moderator in comments to now delete this non-answer.
And here is the point where the moderator disagrees with many of the other users.
The moderator decided to modify Carols posting. He did not add anything, but he deleted 70% of its content. All he left was this:
The correct answer is:
<quote>The name of the actual US-president is Barack Hussein Obama II.</quote>
I do not think, that this part, ripped out of its original context, really is an answer. I believe, that this is just part of correction instruction. And therefore the original answer still is Not An Answer.