Since the honey also happens to be blue in this case, couldn't it be possible that these keepers are wrongfully blaming the M&M's factory? I think the main point of the article was that everyone has their own theory of what the cause is and are all pretty adamant about it:

>Some beekeepers, like Sheppard, swear the berries are to blame for the odd blue honey, which appears intermittently at most, and only in limited hives near the state’s Coastal Plain. Other keepers suspect it might be nectar from the kudzu that grows rampant over nearby fields and forests. Near Dunn, keepers with traces of blue in their hives point to the grapes the bees frequent. And in the eastern part of the state, beekeepers are watchful of the plant Summer Titi, or southern leatherwood.