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rotating whatsit
Those are nice, but I'd argue non essential, especially if all the tolerances are nice enough that it clamps with minimal flex.
That 3mm lip sure is weird, though... I'd expect a minimalist part, from that brand in particular, not to have such obviously wasted metal on it. Maybe it's a dud unit? I'd be tempted to dremel 2mm of that lip out - and by going a hair deeper to ensure fit, that would leave the upper 2mm of the tube less, or not, clamped which would prevent it walking off.
That design doesn't function properly regardless of which frame you attach it to