Well I don't see how this could be a bad thing for anyone. Having Rashad as a training partner for BJ didn't make all that much sense stylistically either, but having top level training partners makes perfect sense. Kenny/Mark are smart enough to create their own game plan for this fight, and I'm sure that stand-up is a major factor.
I will definitely be pulling for Kenny, but I wouldn't put any money on him. Hopefully training with GSP will improve his explosiveness, I'm sure it will improve his cardio. Don't forget that we are probably 4+ months from this fight, so it's not like he's training with GSP full time.