As I write this comment almost everyone else in the thread is interpreting it to mean some variation of an abusive workplace environment. The guy you responded to is being more charitable and less cynical than that.
I think it's actually more cynical than the other comments, because in the case of abusive workplace environments, asking for "gritty" employees is a fairly honest thing to do, and gives a decent indication of what the company is like. Whereas the commenter here was suggesting that the term "gritty" is a nothing more than a meaningless attention getter, and thus totally insincere.