Rama is a very fickle Pokemon when he wants to be. Besides, he wants to prove a point. Even if he doesn't like her, Thyme is important to Bri. Ergo, he has to help her out, no matter what. Besides, he doesn't like Calinth either. The guy smells evil. So for all they know, he could just be doing it because he doesn't like him. Rama is a trickster with odd priorities.