I think you're a great contributor to the site, cde, and I enjoy seeing your answers, but you have a tendency to leave very brief answers, and very brief answers tend to get flagged and/or deleted.
Some questions only require a few lines of text to answer them, but most of the time, the longer an answer is, the better it is, and the more votes it will receive. This is one place where being brief and to the point isn't necessarily a good thing. Longer answers suggest that more thought went into them. A short answer suggests that the user may have been in a rush and didn't put much effort into it.
I'm not saying that you are posting half assed answers - you aren't. I'm just saying that some users might interpret short answers that way. There is also the possibility that people might think you're trying to be The Fastest Gun In The West - plopping down a very curt answer and moving along to the next one.
It appears that in this case, a mod didn't flag your answer - a regular user did - and the mod was simply trying to help you improve the answer. I also think there was a bit of confusion about the thrust of your argument, which could have been avoided if the answer wasn't so short.
I hope you don't think I'm trashing you or criticizing your contributions, because I'm definitely not: I enjoy seeing you around the site and I think you post some great answers. I'm simply trying to help you avoid the repetition of this problem in the future.
(And by the way, the answer as it now stands is great - you have my +1)