Unfortunately for everyone, common sense is uncommon, which is why some of us need helmets. Ians argument seems to be full of common sense to me- the statistics suggesting helmets to be compulsory for bikes don’t add up, even less so for unicycles. A unicycle lacks the pivot point (handlebars) that bikes have that causes people to be flipped onto their head. You are morelikely to faceplant than land on your head- so where are the full face helmet advocates? Common sense is what helmet wearers lack- which is why they need to overcompensate with protection anyway.
By all means wear one if it gives you a false sense of safety… I think we are more likely to die of America’s nuclear paranoia and anti-terrorist bombs than falling on your head.