Well, that is because the work is GPL'd, so.. yeah.  That's the whole point of the GPL.  

If you want to fork your own code and take it private, that's fine, but if you base your work on others who do not agree, you have to re-implement their work from scratch or you are infringing their copyright.  Even if it's 1 line of code.

Do I really have to explain how the GPL works to you?

I'm not judging, per se.  Yeah, it's basically unenforceable for most people.  But ethically speaking, it is unethical.  Then you complain that people steal your code and re-sell it, which is something that is both legally and ethically allowed by the GPL.

Maybe you should write your own miner from scratch if you want full ethical control over your code.