Wait, is the damage caused by an increased risk in prostate cancer or by mental stress? I didn't see anything in the study about mental health.
Anyhow, I do have a couple questions about the study. How early do you need to start in order to see benefits of a decreased risk--when you first hit puberty or can you wait until you're about 40 (I assume that prostate cancer tends to develop later in life). Also, why would frequent flushing of the prostate help decrease risk by flushing out carcinogens as I would think it would be just as likely to let more enter in the first place? I think more study would need to be done.
I didn't say the study talked about mental health. Those are the conclusions I've drawn after years of seeing BIC Mormons and exmormons discussing this issue. I have known people who were seriously depressed and disturbed as teens because they couldn't stop masturbating, no matter how much they want to. I have known one exmormon couple who, when they were active, had a son who considered suicide partly due to dismay this issue created in his life. I do not believe you should minimize the possible impact this has on the mental health of young people in the church.
I agree more study should be done. (not sure why you think that masturbation would be just as likely to let more carcinogens enter, though)