But the point, I believe, is that the concept of breaching the GPL is nonsensical if you do not respect the GPL or the copyright law on which it rests. Whether if you share something against its creator's will, or if you refuse to share something against its creator's will, in both cases you are ignoring the creator's wishes and violating copyright law.
Yes. But speaking in terms of morale, not laws, not sharing the source code for GPL software is morally wrong and dishonorable. Sharing it is morally right and honorable.