You shouldn't be using GPL licensed software for that. End of the story. The person who created that software doesn't want you tp use in your proprietary software and thats exactly why it is GPL. Only Free software are supposed to use them.

Think about it. You cannot use proprietary code of other softwares in your workplace, so why should you be able to use free software in yours? The work done by you for your employer is not benefiting free software, unless yours is also free. So yeah GPL is a "fuck proprietary" license by design. And it does achive its thing. It is good for other free software, and everyone is forced to preserve the freedom in it.