Re: Non-GPL feature
You don't want to use the GPL'd library? Be my guest - nobody forces you to use it. Write your own code for those functions, and you can do whatever you like.
But if you want to re-use code that somebody else has written to save you the cost and bother of re-doing all their work yourself (and doing it properly, which is often hard), then you do it on their terms. If they are fans of open source, their terms may include that you have to add your new product to the open source pile. Like it or lump it.
Or pay damages, of course.