I was going to make a remark about that as well, but I decided against it because I believe /u/nebraska's comment falls in a grey area.
The comment may not be directly rude or offensive, but it is not very hospitable either.
I believe he could have delivered his advice more tactfully, without the kind of tone that often discourages people from posting over at that other website. Not that /u/nebraska didn't have good intentions or didn't contribute to the conversation at all, hence the grey area. I personally feel like this is a situation in which either actions — upvoting or downvoting — are equally justified. Just my two cents. :)