I've thought about this for a couple of days because I thought it deserved serious attention, and I see your point, but a terminally ill patient choosing "the wrong one" between two possible treatment paths when neither of them is likely to work seems like such a corner case that I don't think it should block, or even modify, "right to try" laws.

(And on further thought, magnetic bracelets aren't currently banned, so it seems like a bit of a straw man. I can't think of a woo treatment that could potentially be unlocked by a right-to-try law. I think they're all already available - Steve Jobs' certainly was, to take one famous example).