Yes, they do; it's not abuse when you're given explicit permission. CC BY-SA means you can do whatever you want with it as long as you attribute the source as specified.
danielbarla said that they presented the material under a false name; this goes beyond copying and becomes plagiarism, which I can't imagine is an intended result of the CC license.
Is the source 'User X' or 'StackOverflow'? When you reference CC BY-SA code you don't reference the people who, say, checked it into git but rather the whole repo.
CC BY-SA is short for Creative Commons Attribution Share-Alike. BY means you must attribute, and SA means you must license any distributed derivative works under the same license (copyleft). Attribution on its own is not enough.
