We don't mean to say that he becomes totally powerless.

We don't mean to say that he becomes totally powerless. Later as we describe the meanings of the Qur'anic verse, this point will become clearer. This person is in the path of the torrent that just pushes him along. He wants to struggle against it but is unable to do so. He observes that all these people are going towards hell and they are pulling him along; so he wants to return from the path to hell. (But he is helpless.) Have you been stuck in a mob?