Worrying about free software advocates using the law against others is hilarious. It's like worrying about Walmart cashiers demanding to make more money than software developers.
Don't get me wrong, I love the GPL, I love free software! Choosing a license though, GPL or proprietary, is entirely up to the author of a piece of code though. Forcing open licenses upon authors is detrimental to freedom in general.
Worrying or not worrying about it has nothing to do with the ethics of breaking the GPL (or any license).