https://theconversation.com/im-an-mlk-scholar-and-ill-never-be-able-to-view-king-in-the-same-light-118015

Bunch of left-wing sources dismiss these claims as unreliable since the tapes they're based on are still classified. They declassify in 2027.

This market considers only what's on the tapes, not whether the tapes themselves are fabricated, nor any other evidence that emerges. If the tapes are never released, perhaps because it's discovered that they've been destroyed, this resolves N/A.

"Participated in" includes "watching from the sidelines and doing nothing about it".