Can the ergot proposal be tested at all, or is the kykeon permanently out of reach?

The proposal was made in 1978 and has been argued over since without anything being settled, because the argument runs from the reported effect back to a cause that would produce it rather than from evidence of the cause. Nothing ancient describes the drink as intoxicating, and the delicate preparation the chemistry requires is nowhere recorded. The initiates kept the oath for roughly two thousand years, so the documentary route may simply be closed.