The Short Version
Apple reportedly delayed camera AirPods because Siri's visual intelligence software is not ready, not due to hardware problems, per a WIRED source.
Apple's camera AirPods are reportedly being held back not because the tiny cameras don't work, but because Siri can't yet do anything useful with what they see. The hardware is ready; the software that would let Siri look at the world around you and respond intelligently is not. Shipping cameras without that feature would make them pointless, so Apple is waiting.