While anything is possible, it's most likely the scenario where the bag was taken by mistake. I've experienced where others have fetched my bag by mistake and vice versa. These days, all bags appear to have a basic design, and I now have a much higher appreciation for those with a penchant to personalize their rollers with stickers and decals.

However, what's puzzling to me are 1) the insistence by the crew the passenger disembark before searching for the bag and 2) assurances that it would be found in the carousel (baggage claim). As with others, I would likely have insisted to search the area where my roller had been, at the very least.