It kinda confuses me too... I think he was going to take kimimaro before he realized there was someone better... that person being sasuke. But, since Sasuke didn't arrive in time, he took the prisoner man instead (WHICH doesn't make too much sense to me because he could have just used kimimaro instead)

So yeah... that's what confuses me... he ditched kimimaro over sasuke, but didn't take him even when sasuke didn't arrive in time for the body switch.. Maybe he is depending on Kimimaro to bring Sasuke to him? ^^ That's all I can think it could be..