If I had an effective product/therapy, I would leave the comments open, as the positive comments and success stories would eventually overwhelm the negative. Blocking them doesn't guarantee that the product/therapy is ineffective or risky, but it does raise questions.
You're right that every medicinal/therapeutic, even aspirin and liver, can have side effects, so doesn't it make sense for someone to provide warnings about the risks, rather than just the potential benefits? In the USA, the law requires reporting potential side effects with every Px drug, so I'm not sure what you're referring to about no warnings for drugs. Of course, Big Pharma only does it because the government forces them to, and often the warnings are incomplete or insufficient, but every Px drug does have at least some. Wasn't snake oil sold without prescription by mostly relatively small operators, much like Humble and Kalcker, rather than Px meds sold by large drug cartels?
I investigate the potential side effects of all therapies, not just Px drugs, and I don't just go by the word of sellers of either Px drugs or complementary/alternative therapies. I try to do some investigating of my own, which fits with the frequent advice in this forum to learn more about the foods/foodlements/supplements/cosmetics we use, the producers of them and how they are made, which especially makes sense for those I've never used and haven't seen any skeptical, critical analyses of.
Have you investigated the possible side effects of the MMS therapy? Is Humble and Kalcker's selling of MMS-related stuff a potential profit motive? How is the MMS sodium chlorite manufactured? Where do the people who buy the barrels of it get it from? Have you Googled MMS and checked out any critical sources of info on MMS beyond MMS sellers and promoters like Jim Humble, Andreas Kalcker, and their supporters?
If you didn't witness the people your friend treated, how do you know he cured them with MMS, including of cancer?
If the answers are promising, I might investigate further.