That's the cool part about chemistry, when used in this synthesis the dichloromethane becomes a whole new (presumably safe, but we'll see what further testing turns up) molecule. Sodium is explosive and Chlorine is highly corrosive, but combine them and you get regular old table salt. Just because a reagent is dangerous doesn't mean the products it creates will be.
Edit: I just did a little research and it looks like 3,3′-Diindolylmethane (DIM) is safe for human consumption. It's already sold as a dietary supplement. It's marketed to help with metabolism of estrogens but we all know how "trustworthy" the dietary supplement market is.
And the distinction between those two is???? A religion is merely a cult that has gathered enough followers to go mainstream.