That's fair. OP's argument boils down to, "I'm protesting divisive 2 party politics by going independent", so the only real way to change OP's mind is, either A: Prove that 2 party systems are preferable, or B: Prove that being an Independent is not an effective protest. I chose B, even though it's a difficult argument, because of the typical counter arguments of "it's better than nothing". There's no real way I see of changing his view with point B, but I can definitely expand it and make them consider other forms of protest and why being independent may not be the best form.

If anything, it's food for thought for them or others.

I was just awarded a Delta though, so I did some work in changing some perspective, even if I didn't really hit the core of it, which as above, I think is practically impossible (Better than nothing).