I see someone hasn't had GPL conflicts in their code base before. There is a reason companies specifically look for them and it's because the FSF and it's communities will make your life hell.
Try using proprietary libraries in your software without complying with their licenses and you'll see what having your life made hell means. GPL license holders barely ever sued anyone, and when they do (like FSF v Cisco), it's usually after years of trying to get them to comply. That they (rightly) complain about your practices is not using the law.