Nope, I'm no expert on chairs(!) but this isn't even debatable. It's just plain dangerous

a jubilee clip is not a structural fixing, not ever, not even "to prevent rotation" or "done in anger"... and don't start me on using car exhaust clamps in that way. FFS, he'll be lucky to get away with a flaming for it and not a visit to casualty/the morgue.
I understand broke, and I understand bodging, but that is just stupidity in action.
I feel the need to add, please please please, if anyone is reading this and thinking of fitting a chair, please speak to some of the members on here who have chairs, and some of them a great deal of experience who can save you from expense and injury, but whatever you do DON'T copy this guys example
