I agree that that would be fair, but we should also acknowledge that usually an IC doesn't actually have any leverage in this situation, although this depends on your location and particular employment situation. Typically (and maybe this is changing) a US software developer is employed overtime-exempt at-will, right? So, you can ask for this, but as per your employment agreement, they can absolutely demand this of you and let you go if you don't agree. I'm not arguing that is the way that it _should_ be, just that to my knowledge that's the way it usually is.

Edit - you say you're willing to quit if they don't agree, so I guess you're up for this possibility. More power to you!