I agree with you mostly CVille, but I have to admit, I think fiatlux is ADORABLE! He's trying really hard here and searching for that button that's gonna get us all riled up, and I think it's pretty stinking cute. I'm gonna dignify his attempts with a little bit of an answer. A teenie one just for funsies.
1. fiatlux, (so darn cute!), typically when a team leaves a conference, conference-mates don't say nice things about them. Ever. Nobody had a nice thing to say about nebraska when they left the Big XII either. Not a single one that I heard. aTm is still getting hate for leaving the Big XII and just the other day, even Dodds was piling on Mizzou in public. What possible incentive would there be to say something nice about a departing team?
2. A big part of the nebraska fan base's identity was explaining to anyone who would listen that we were not their rival. They were especially fond of explaining that one point--again and again--on our CU Fan sites and in the remarks sections of our Colorado newspapers. Their point was that the W/L was so lopsided (admittedly) that it couldn't be a real rivalry. Also (and I heard this one A LOT), they hated us too much to be our rivals. Think about that for a minute. They hated us too much to be our rivals.
3. Of course for a number of years Colorado and nebraska played the marques game, the Friday after Thanksgiving. Oh, and nebraska has torn down their goal posts more times following a victory against CU than against any other team (yeah, yeah, they got more chances...got it). Also, interestingly (as already pointed out) Oklahoma didn't really consider nebraska to be their rival. Nebraska talks about their rivalry with Oklahoma being built on respect (not hate), but I've never known a fan from Oklahoma to admit that he/she knew what the **** nebraska fans were talking about.
4. But here's where I get to my real point. You suggest that both teams have to agree to the rivalry. I disagree. That nebraska didn't consider it a rivalry (hint: they did, really) didn't diminish my gameday experience one bit. Because I believed it to be a rivalry. And I hated that self-congratulatory, obsequious, runza-fed fanbase with every ounce of my being (still do). Do they really have to reciprocate for it to matter? Or can I treat every Friday after Thanksgiving as my own personal Christmas without that emotion being validated by a bunch of red-polyester-wearing cadavers? I'd argue that the hate that lies in my heart requires no validation from anybody else--it's belongs to me--and even if I approach(ed) each nebraska game day like some retarded guy, who didn't know he was retarded, cheering quixotically in a rivalry that was unrequited, the emotion heightened my personal football experience and that is all that mattered.
5. Finally, thank you so much for stopping by and participating in the conversation, luxie. You're welcome here anytime. Next time it would be super if you posted pictures of your tits, though.