That quote seems a little too vague to me. After all, what a putthajana would feel joyful about would be as a consequence of being ignorant about its inherent Anicca nature. Therefore, that wouldn’t be something to rejoice in. It makes more sense that mudita would be rejoicing in others conducting themselves in such a way so as to increase the likelihood of them getting onto the path and/or progressing along it (i.e., cultivating the mundane and noble paths).
A Quest to Recover Buddha's True Teachings
