Ubisoft has a long standing tradition of abusing the fact that a perceived exclusive attracts more attention. For that reason alone, any comments on exclusivity from their end means nothing to me other than that it will most likely be a timed exclusive and the 360 game won't be there for at least 6 months. It's a viable strategy for multi-platform development, because you can first focus on the first platform, and then on the second, and you can save some money should the project fail.
Free Radical can do whatever they want. If they want to put it on 360 then they will, if they don't, they won't. Ubisoft needn't have much to do with this.