Like most free advice, Mohler's seems to be worth every penny, and here's why. This man is offering no licensed medical advice on the subject, and it is clear that he has done little research on treatments related to sexual disorders. He claims that "sin" cannot be treated, but clearly Weiner is not trying to treat his previous actions, which cannot be undone. Rather, he is seeking treatment, presumably to understand and therefore avoid some of the irrational, perhaps even obsessive behaviors in which he engaged. Obsessions can be, and frequently are treated quite successful, Mohler's apparent ignorance on the subject notwithstanding. The same goes for irrational ideations, which are frequently addressed in therapy.
Jesus may or may not be able to forgive Weiner for his actions. Some of them, such as the sending of the single x-rated photo, if legitimate, may arguably cross the line into marital infidelity. Weiner's wife, being the injured party, would be the primary from whom atonement should presumably be sought. Given that she is a Muslim, it is unlike that she would want to involve Jesus as a third-party mediator here.
As a consequence, we have to conclude that Mohler could not have been altogether genuine in his suggestion. He had no reasonable expectation that he would convert a Jew or a Muslim to his brand of hard-line Christianity. Instead, he just wanted to exploit the present circumstances as an excuse to proselytize. He was just reminding his own base, as thought they did not already know, that Anthony Weiner is not one of them.
I would like to suggest that Congressman Weiner is not the only person who needs therapy. Mr. Mohler could probably benefit from therapy to treat his own obsessions with evangelical Christianity.