When I saw Penn & Teller live in the same show they did the routine you describe, but also a fire eating routine about how some stunts simply do hurt, and can be dangerous to both learn and perform. Neither break the "no permanent damage" rule but you are left with two seemingly contradictory arguments.

Properly aligned you can fit the two ideas together, but I think they kind of personal mental arranging of ideas is exactly what they want to leave you with.