Yeah, I don't think Riku meant what he said to Roxas in their last conversation completely as "I'm not willing to look for alternatives in Aather" either. Just that he doubted it was possible. But to Roxas, someone who was genuinely sorry would jump on the smallest, most pathetic chance to fix what they'd done wrong. He would.

I think Riku is willing to look for alternatives - and did in canon to some extent - but he has to get past 'willing' and into 'active.'